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NesikaPPC
10-22-2013, 03:10 PM
I am trying to decide between two calibers. I want to change a rifle to a 6.5 caliber. I am stuck between a 6.5 - 284 Winchester and a 6.5 -47 Lapua. I know a little about the -284 and little to nothing about the x47. Any ideas or opinions?

Thanks

James M.
10-22-2013, 03:27 PM
Personally, I would opt for the 6.5x47. It has great accuracy in most barrels and has far better barrel life. Good shooting....James

NesikaPPC
10-22-2013, 03:40 PM
Will it fit in a short action, and does it use a .473 bolt face?

Jefferson
10-22-2013, 04:43 PM
what are you going to use it for, need details and then we can let you know the differences that exist for the range (distance) you will be shooting it from and to, also the competition or just from a bench makes a difference, in other words what are you trying to achieve

Jefferson

alinwa
10-22-2013, 04:56 PM
All else being equal, the 6.5X47L is a better chambering. It's inherently more accurate, barrel life is better and it's almost as fast with significantly less powder.

Lee Martin
10-22-2013, 06:49 PM
Both are outstanding and with Lapua producing the brass quality hulls aren't a problem. That said I'd probably pick the 47. Better barrel life while only giving up 100 fps over the screens would be the reasons. Good luck and let us know which one you chamber.

-Lee
www.singleactions.com

SGS
10-22-2013, 06:56 PM
Will it fit in a short action, and does it use a .473 bolt face?

Yes and yes. The 6.5 X 47 is shorter than .308 based cartridges and allows seating longer bullets long enough to maximize case capacity and still fit in a short action magazine. The 6.5 X .284 can be a headache in a short magazine and may also be difficult to get to feed smoothly. I like both cases, but I would use the 6.5-.284 either in a long action or a single shot.

Scott

NesikaPPC
10-22-2013, 09:16 PM
Jefferson,

I am looking for a gun to be primarily a long range varmint gun. I doubt it will be a competition gun, but it will get shot off of a bench. I have a short action to work with, so I am trying to use what I have.

alinwa
10-23-2013, 01:39 AM
The 47L case will take significantly more pressure than the -284 case and as such will actually push light/medium bullets just as fast as the much larger case!

al

R.DesJardin
10-23-2013, 07:32 AM
The 47L case will take significantly more pressure than the -284 case and as such will actually push light/medium bullets just as fast as the much larger case!

al




What testing equipment and or method did you use to reach this conclusion?

Lee Martin
10-23-2013, 09:49 AM
The 47L case will take significantly more pressure than the -284 case and as such will actually push light/medium bullets just as fast as the much larger case!

al

That's news to me. I'm also curious to know how that was derived. Not arguing that folks don't push the 47 harder but as for the brass being stronger?

-Lee
www.singleactions.com

NesikaPPC
10-23-2013, 10:30 AM
is the x47 a capable varmint round out to 1000 yds?

Bill Scheider
10-23-2013, 11:27 AM
:cool:

alinwa
10-23-2013, 02:03 PM
What testing equipment and or method did you use to reach this conclusion?


???

The rifles themselves.

You don't need copper crushers or modified chambers for this....... in fact these tools are of limited facility even in a testing lab. In the end, the limiting factor is and will always be the cartridge case itself. Some cases take more pressure, some brands of case take more pressure. It's simple fact that you can't achieve the same velocities using Norma brass as you can with Lapua or Winchester. And in all cases the working limits of the bolt action rifle aren't even approached prior to case failure.

Just like the PPC/BR cases and the new 308 Palma case the 47L case has more head support, small flashhole and small primer pocket. The limiting factor on any assembly is casehead support, once primer pockets begin to open up (a function of casehead expansion) you've reached the pressure limits of the case. My 6X47L comp guns push 105's to 3250. I've got cases fired nearly 100 times at 3150fps. This is significantly faster than ANY "comparable" case (6XC/6-250/243AI/6MMAI etc) and nearly equal to the 6-06, beats the 6X284 in most rifles. The 284 case is a low-pressure case due to it's design, the primers get loose at low pressure. The other biggy is brass "flow" into the ejector hole, most often this occurs AFTER casehead expansion. Generally by the time the shooter sees shiney spots the pockets are loosening.


Some companies know this, actually most of them "know" is but only Lapua and Winchester have actually acted on the knowledge. Lapua designed the 338L SPECIFICALLY around the casehead structure. They knew perfectly well that to reach the velocities they wanted in the case size they wanted they had to design the case to take pressure.

The 338L is one of three case designs which come to mind where the structure of the casehead is such that oftentimes one will show brass extrusion into the ejector hole before pockets loosen. Another is the WSM/WSSM cases, these rounds are typically run TOO HOT from the factory. Mainly due to pre-release hype and unrealistic consumer expectation the factories choose to load their offerings so freaking hot that cases are ruined in the first firing! (This put a lie to the idea that testing cases to failure is somehow "unsafe") I shoot the WSM case in several incarnations and have built a number of them for clients. I also custom load for people, (07 FFL) and generally my loads are slower than factory offerings.

Because factory loads are often too hot.

And they KNOW this, but they're stuck. Kinda' hard to sell a "short 30-06" in today's market.

Incidentally, this is pressure thing the reason the 6PPC rules the accuracy roost. I _can_ and have, along with many others, built cases that will compete with the 6PPC but it's a lot of work to make cases that better the performance of the 22R. Same can be said for the 6BR case. When I first claimed 2900fps using 105's people scoffed. Here on this forum, back in the early '90's I was called a liar. I spent MONTHS defending my position, begging with people to TRY IT using fitted FL dies and sloooowly but surely the concept gained traction as people across the nation tested it out.........Since then there's a website built around this ONE CASE and it's various iterations. It's been fun to watch.


I've built and tested thousands of cases using large primer VS small primer in the same capacity cases and the difference is stark. I ordered 500 of the 6.5X47L cases over a year before they shipped to the US..... I had two reamers waiting and three barrels chambered up BEFORE THE CASES WERE AVAILABLE. And they're awesome. And they kick Tubbs 6XC case to the CURB. (This is relevant only because GD recognized the problem and contracted to have cases made at great expense. And JUST as his project reached fruition the 6.5X47L case hove over the horizon, bummer!)

Same with the 308 Palma, I pre-ordered them as soon as they were projected.


Same with the 6.5X47L case VS the "Dasher"....... The DAsher was an inspired case, two wicked smart people designed the Ultimate 22 Verminator and called it the DAsher. Since then it's been corrupeted into the "6 Dasher" and become wildly popular because IT WORKS! It WINS because a select coterie of gunsmith's have worked the bugs out.....then along comes the 6.5X47 case and guys like me hooted wildy "here's the answer!!!"


And it IS..... it has all the necessary features. It IS a stretched BR case.....it HAS TO work.....


But silly people, slobbering chambers into rifle using "Go Gauges" have managed to bugger up enough rifles that a large segment of the competitive shooting population believes the 6X47L to be somehow "less accurate" than the Dasher....

OK, enough digression. But it's all relevant to the original query. And YES the X47L is "capable" at 1K, as capable as any other 6.5 or 6MM on the planet.


IMO better than anything else on the planet.




opinionby






al

Jefferson
10-23-2013, 08:59 PM
based on your needs I would go with the 6.5 by 47 as there are some very nice berger bullets out there, barrel life is better then the 6.5 by 284 and a little less recoil and the 6.5by47 is very accurate,

so if you do not need the little difference in windage at 1000 yards the 6.5 by 47 will do quite nicely with lapua brass and berger or equivalent bullets and some powder 4350 brand perhaps,

try the 6mmbr.com website for further particulars on the 6.5 by 47

later and have fun


(ps build a gun with a anschutz rail with a remple biopod and have some real fun)

Jefferson

alinwa
10-24-2013, 12:30 AM
The thing is..... the various ammunition/rifle makers and even more importantly, the various writers of reloading manuals have to accommodate the whole world..... every Tom, Dick and Hairy and their appurtenant cat. AND, even then, THEY DON'T!

We just had a thread a couple daze ago illustrates this point. Dude COULD NOT, would NOT accept that with HIS gun he was pressuring out at well below "the loads in the book."

In the end the ONLY responsible, the ONLY safe thing to do is to learn how to establish YOUR OWN personal MAX loading for each and every barrel you load for. And for this there is precisely ONE accurate indicator, industry-wide, fuh'GEDDAbout CUP and PSI and crushers and bomb guns and strain gages and se and learn that THE ONLY real indicator is casehead expansion. Every one of the other methods has accuracy parameters, some of them, like the strain gage method are not only inaccurate but are dependent on reading thru a threaded joint and as such vary wildly from setup to setup, are useful only as comparators.


Casehead expansion is absolute. It accounts for variables like case age and hardness. It's independent of chamber fit and rifle construction.

It's dependable.

It's REAL.....

STAY BELOW IT!!!!

al

R.DesJardin
10-24-2013, 07:41 AM
The thing is.....

Casehead expansion is absolute. It accounts for variables like case age and hardness. It's independent of chamber fit and rifle construction.

It's dependable.

It's REAL.....

STAY BELOW IT!!!!

al

Yes it is a good gauge. But it is dependent on chamber fit and rifle construction. The case expands beyond it's elastic limits which a loose chamber or lighter built rifle would definitely have an effect on.

NesikaPPC
10-24-2013, 11:18 AM
Not trying to ask an incredibly ignorant question, but I have only done a small amount of reloading, and it was pretty conservative. When you talk about pressure signs, case head expansion, etc., what and where do you look for pressure signs. I've also heard about pierced primers but never experience those. What are there causes/remedies?

Thanks in advance for indulging in questions from a relative beginner.

alinwa
10-24-2013, 06:35 PM
Yes it is a good gauge. But it is dependent on chamber fit and rifle construction. The case expands beyond it's elastic limits which a loose chamber or lighter built rifle would definitely have an effect on.

Absolutely false...... as you would know if you'd ever tested it.

I have.

I have tested for tenon size/thickness,

for receiver thickness and barrel joint loading

and for boltface size.

There is NOTHING to contain the casehead, it just floats in the air.....

and if you DO build to contain the casehead (I have) you will end up with a two-handed Wichita action :)

Please, if you insist on making proclamations, tell us how you arrived at your conclusions. Say more than "would definitely have....."

You describe for me a testing procedure and the mechanics of a containment mechanism and I'll take it at face value.

Altho, be warned, I WILL TEST IT!

I test everything.

al

alinwa
10-24-2013, 07:24 PM
Not trying to ask an incredibly ignorant question, but I have only done a small amount of reloading, and it was pretty conservative. When you talk about pressure signs, case head expansion, etc., what and where do you look for pressure signs. I've also heard about pierced primers but never experience those. What are there causes/remedies?

Thanks in advance for indulging in questions from a relative beginner.

There is ONE incredibly ignorant question.....

I didn't say "one ignorant question allowed," I said "there is ONE ignorant question....."

The only ignorant question is THE ONE YOU DIDN'T ASK!!!

We're raised in a culture where we, as guys are expected to be able to rebuild a T'ree-Fitty Chubby using only our leatherman tool, IN the dark, ON the trail at twenny below zero, plus remember all the torque specs axle-to-axle and be able to set them reasonably well with said leatherman tool.....

and smile about it.


We're just supposed to KNOW stuff.

.....and people like my own father will drive around the county for HOURS instead of stopping to ask directions.....

Life's too short,

then you die.

So I ask LOTS of questions.

And here are the answers to your specific questions.

Cashead expansion..... the one TRUE gage......

Right now about every third "high-end reloading" article and about every other cutting edge reloading manual touches on the subject and invariably they tell you to get a "blade mic" and measure for it.

DUMB!!!

First of all, once't you've spent the money for a blade mic (I have) and you start actually measuring caseheads you begin to realize that "DUDE! it's an imperfect world!" IF you actually DO this, if you embarque on this mission f'real, you will soon have cases marked in about 5 different colors of Sharpie, cases with notches filed in them and bags and boxes of sortments but most of all you'll have 6 mo worth of cases which are marked "???" because you've just now worked out your filing system..... your NOTEBOOK to keep it all organized.....

If'n you're under twenny you'll have a file folder in your fone....

Buttinnyways, about the time you actually arrive at a meaningful method you'll also realize that those cases which are to be culled out all have "loose primers." What that means is, when you go to re-seat a primer, it goes in LOOSE. Loose enough sometimes that they'll actually fall out if you tap them on the table. At this point guys like me seat ONE MORE PRIMER over cigarette paper, daub it with a liddle Bob-N-Roys and stick it in the box as a throwaway varmint round.

But I digress.

Don't YOU do this, in facto forget I ever said it.


The PROPER way is to throw away the cases one firing after you feel a change in primer seating resistance....... IF YOU DO THIS, and if you are a careful reloader using good technique you will never leak a primer.

Leaking a primer....what it is and what it means.

This was gonna' be your next question.

Once your primer pockets begin to expand (casehead expansion) the primers get looser. They SEAT looser, you feel it when you seat them. When they get loose enough, they begin to LEAK. Super-heated gases escape around the rim of the primer. This isn't dangerous per se, it smells funny and _may_ make your eyes sting a little, but IT WILL RUIN YOUR BOLTFACE!!!

It's called "gas cutting" in the common vernacular and it makes a ring around the firing pin hole. A cratered and pitted ring over time.

So you don't want it.

THROW THE LOOSE CASES AWAY.

You can't fix them. (I've tried)

I have bought three tools purported to re-swage or otherwise fix expanded primer pockets and they do not work for me. Others report success.

Which brings us to "Primer Piercing."

First of all, the term is a misnomer. Primers are never "pierced," there is no mechanism for it. Primers are "popped" or "blown" or, correctly, "blanked." Primer blanking is the result of pressure being high enough to shear out a disc of material roughly the size of your firing pin hole and blow it into the bolt body. There are precisely TWO cures for blanking. #1 is to back the load down. #2 is to make the firing pin hole smaller. A "typical" firing pin hole is somewhat north of .080 in diameter. A "benchrest" firing pin hole is smaller, like mebbeso .065 or somesuch. In between are a range of "medium pressure capable" firearms.


hth


al

alinwa
10-24-2013, 07:28 PM
BTW, what you're striving for in the reloading game is to get your setup dialed in until you can reload a case 20...50........even 100 or more times without a case failure. I do this with a wide range of cases from 220R up to and including a blown out 338L.


Easier said than done.


UNDERSTAND "incipient casehead separation!"



al

John Kielly
10-24-2013, 07:58 PM
al,

Maybe you missed one possibility, or needed a bit more explaining.

A case might continue to be used in some circumstances when it loosens up if a larger diameter primer of suitable performance is available.

Did I qualify enough?

John

alinwa
10-24-2013, 08:17 PM
al,

Maybe you missed one possibility, or needed a bit more explaining.

A case might continue to be used in some circumstances when it loosens up if a larger diameter primer of suitable performance is available.

Did I qualify enough?

John

I've heard of this, never actually experienced it :)

There was a time when folks were claiming certain Federal offerings were wider. Also CCI's....

But I can't confirm it from my experience.

al

R.DesJardin
10-25-2013, 11:37 AM
al,

Maybe you missed one possibility, or needed a bit more explaining.

A case might continue to be used in some circumstances when it loosens up if a larger diameter primer of suitable performance is available.

Did I qualify enough?

John

You've stretched the case past it's yield point and I wouldn't want to reuse it. Brass work hardens very easily then become brittle as does many metals. I've seen mild steel do this also, worked hardened and become so brittle it fractures.

mks
10-25-2013, 12:40 PM
You've stretched the case past it's yield point and I wouldn't want to reuse it. Brass work hardens very easily then become brittle as does many metals. I've seen mild steel do this also, worked hardened and become so brittle it fractures.

We stretch the neck of the case past its yield point with every firing, and with every resizing. Unless there is some other problem, we can go past yield hundreds (thousands?) of times without failure. Steel has failure stress close to yield stress after work hardening. Brass doesn't. There is no reason to worry about case heads getting brittle and cracking under normal circumstances.

Excessive shoulder setback is an exception. In this case, the brass goes WAY past yield and the case head pulls off the body.

Cheers,
Keith

R.DesJardin
10-25-2013, 01:18 PM
We stretch the neck of the case past its yield point with every firing, and with every resizing. Unless there is some other problem, we can go past yield hundreds (thousands?) of times without failure. Steel has failure stress close to yield stress after work hardening. Brass doesn't. There is no reason to worry about case heads getting brittle and cracking under normal circumstances.

Excessive shoulder setback is an exception. In this case, the brass goes WAY past yield and the case head pulls off the body.

Cheers,
Keith

Sure maybe he can buy some primer bushings since the case is still good.

alinwa
10-25-2013, 10:37 PM
We stretch the neck of the case past its yield point with every firing, and with every resizing. Unless there is some other problem, we can go past yield hundreds (thousands?) of times without failure. Steel has failure stress close to yield stress after work hardening. Brass doesn't. There is no reason to worry about case heads getting brittle and cracking under normal circumstances.

Excessive shoulder setback is an exception. In this case, the brass goes WAY past yield and the case head pulls off the body.

Cheers,
Keith


Not to quibble but I fail to see a connection here...... casehead separation is not the result of brass being stretched or distorted and then put back, like the neck or the casebody. It's the result of repeated stretching to the point of separation. Head separation is a one way street.

al

mks
10-30-2013, 12:38 PM
Not to quibble but I fail to see a connection here...... casehead separation is not the result of brass being stretched or distorted and then put back, like the neck or the casebody. It's the result of repeated stretching to the point of separation. Head separation is a one way street.

al

My point is that brass doesn't get brittle like steel. Brass is a ductile material. See the plot on page 3: http://people.virginia.edu/~lz2n/mse209/Chapter8.pdf Casehead failure is ductile.

The web above the casehead does thin before it fails. But it thickens some during sizing. So there is some back and forth on that, ultimately, one way street, which makes it similar to sizing necks. Necks stretched excessively in a large chamber fail by the same mechanism.

Just another observation: Thin spots in the web concentrate the stresses, and these areas thin faster. We spend a lot of time turning necks to make them uniform thickness, which uniforms the stresses. But not many machine the body, or even inspect for uniform bodies.

Cheers,
Keith

alinwa
10-30-2013, 08:32 PM
My point is that brass doesn't get brittle like steel. Brass is a ductile material. See the plot on page 3: http://people.virginia.edu/~lz2n/mse209/Chapter8.pdf Casehead failure is ductile.

The web above the casehead does thin before it fails. But it thickens some during sizing. So there is some back and forth on that, ultimately, one way street, which makes it similar to sizing necks. Necks stretched excessively in a large chamber fail by the same mechanism.

Just another observation: Thin spots in the web concentrate the stresses, and these areas thin faster. We spend a lot of time turning necks to make them uniform thickness, which uniforms the stresses. But not many machine the body, or even inspect for uniform bodies.

Cheers,
Keith

No.

Simply, no.....

You're misunderstanding the mechanism of casehead separation.

The web above the casehead thins because the brass keeps pulling away from it due to improper sizing. It does NOT go "back and forth like the neck" in fact it will never thin at all if one's dies are properly matched. I can and do resize cases untill they wear out from other things, like the flashholes burn out, and show ZERO thinning at the casehead.

Casehead separation is quite simply a function of improper sizing and can easily be avoided in it's entirety.

The mechanism is this: an improper setup first sets the shoulder back too far, then the force of the firing pin drives the case forward opening a space between the casehead and the boltface, the case expands and LOCKS IN PLACE in the chamber and the casehead is driven back to the boltface by internal pressure.

Do this enough times and the casehead simply pulls off the case....... no "back and forth."

Bottom line, IF YOU'RE TRIMMING YOUR NECKS, you will get a casehead separation sooner or later.


Interestingly enough it takes quite a bit of pressure to stretch the cases on new brass........... I'ma' SWAG around 50,000psi....... Many loads are low enough pressure that the casehead never goes back to the boltface, the gap stays there and the primer "pops up" above the casehead. You _could_ fire most factory 30-06 loads using a hammer and nail simply holding the nekkid barrel in your hand and the case wouldn't leave the barrel!

:)


Nor would the case ever suffer a casehead separation.


Brass more than 30yrs old will sometimes break because it's embrittled by age, but this is again, a different problem.


al.

mks
10-31-2013, 12:06 AM
You _could_ fire most factory 30-06 loads using a hammer and nail simply holding the nekkid barrel in your hand and the case wouldn't leave the barrel!


PLEASE don't try this. Whether you do back-of-the-envelope calculations or full-blown computer simulations (see http://www.varmintal.com/a243z.htm), the web deforms plastically. Even with the minimum bolt thrust from Al's simulations of 4 ksi, the stress in a 0.030" case wall is 96 ksi, which exceeds the tensile strength of all but hardest of hardened brass.

alinwa
10-31-2013, 02:01 AM
PLEASE don't try this. Whether you do back-of-the-envelope calculations or full-blown computer simulations (see http://www.varmintal.com/a243z.htm), the web deforms plastically. Even with the minimum bolt thrust from Al's simulations of 4 ksi, the stress in a 0.030" case wall is 96 ksi, which exceeds the tensile strength of all but hardest of hardened brass.

Parker Ackley did it :) He removed the locking lug from a 94Win and fired it with only his fingers holding it shut.

But then P.O. was a doer, not a simulator.... he practiced what he preached.

I'm not advocating unsafe behaviour I'm simply illustrating that most middle-of-the-road setups have very little bolt thrust. Regardless what the numbers (or computer simulations) say once one becomes aware of the phenomenon it becomes almost second nature to check for popped up primers, they're quite common.

al

alinwa
10-31-2013, 02:12 AM
Incidentally, Varmint Al's computer predictions show catastrophic gasket failure at pressures well below where BR is practiced....... like in real life 95% of the cases on the firing line SHOULD BLOW OUT, simply cannot be working according to his simulations.

I've argued with him about this very subject here on this very board :) he's the only guy I know who'll argue with fact. He told me that the typical BR setup "could not work" because the brass cases couldn't contain the pressure...


"But"..... I said....... "they do!"


I've got guns that run at 30,000psi over "catastrophic failure." For dozens, even hundreds of reloads/case.

mks
10-31-2013, 10:07 AM
Parker Ackley did it :) He removed the locking lug from a 94Win and fired it with only his fingers holding it shut.


For a 30-30. You can bet he never did it with a 30-06. The cross sectional area of the case is 24% larger and the SAAMI pressure is 43% larger, for (ball park) 77% greater stress in the brass.

alinwa
10-31-2013, 11:48 PM
For a 30-30. You can bet he never did it with a 30-06. The cross sectional area of the case is 24% larger and the SAAMI pressure is 43% larger, for (ball park) 77% greater stress in the brass.

True, but talk to any Palma guy about spent cartridges "rocking on the primer."

I typically start working up loads such that my "starting loads" aren't capable of stretching the case..... somewhere in the workup the cases begin to give, and my typical working pressure ends up well above the pressure required to rip the case apart. ANY case...... I just run the tough ones hotter. Generally my loading/shooting is accomplished within the top percentile, near unto case failure but I don't accept anything less than 15 reloads/case for hunting rifles, 50+ for target stuff.

And while I've blown off caseheads back in the day, I will never again.

al

mks
11-01-2013, 09:44 AM
True, but talk to any Palma guy about spent cartridges "rocking on the primer."


If you are saying that the raised primers are evidence that the casehead never touched the bolt, that is not true. For a typical high pressure load, as chamber pressure rises, the primer is pushed out to the bolt face first. Then as pressure rises higher, the casehead is pushed out to the bolt face. The primer slides back into the pocket as this happens. As pressure decreases, the casehead recedes away from the bolt face first, minus any plastic deformation. There still being some remaining pressure, the primer remains in contact with the boltface as the casehead recedes, until the pressure decreases below the level required to overcome the friction between the primer and the primer pocket. After all is said and done, the primer extends beyond the casehead, even though it didn't at the peak of the pressure pulse. You can see this occurring in VarmintAl's animations.

Cheers,
Keith

alinwa
11-01-2013, 10:40 PM
If you are saying that the raised primers are evidence that the casehead never touched the bolt, that is not true. For a typical high pressure load, as chamber pressure rises, the primer is pushed out to the bolt face first. Then as pressure rises higher, the casehead is pushed out to the bolt face. The primer slides back into the pocket as this happens. As pressure decreases, the casehead recedes away from the bolt face first, minus any plastic deformation. There still being some remaining pressure, the primer remains in contact with the boltface as the casehead recedes, until the pressure decreases below the level required to overcome the friction between the primer and the primer pocket. After all is said and done, the primer extends beyond the casehead, even though it didn't at the peak of the pressure pulse. You can see this occurring in VarmintAl's animations.

Cheers,
Keith


Ummmm, no.

This is the problem with Varmint Al and his cartoon guesses. Some of his assumptions are just WRONG :) You can perty much make a simulation "show" anything.... it's called GIGO or "make a piss-poor assumption, get a piss-poor result"...... In the real world primers vary in their protrusion with some of them popping up 3-4thou, FAR BEYOND the springback of the brass, which in any case couldn't exceed a thou. (Really, caseheads don't spring back at all but we'll leave that be for now)


Even testing is a slippery slope, let alone this silly "simulation" garbage.....Don't get me started on the "tests" where weighted brass, copper and gilding metal sheets were dragged over surfaces to "simulate conditions inside the chamber." in an attempt to disprove the FACT that cases stick. A fact easily proven using solid testing methods.

This is FACT, primers often pop up several thousandths....

This is also FACT, under normal conditions, cases stick.....

And it's FACT that if you stretch a case or any tube of brass 3-4thou longitudinally over a distance of 15-30thou IT AIN'T SPRINGING BACK!

Now, you show me a mechanism for driving that silly phallic casehead story and I'll TEST IT...... if in FACT them pumped up caseheads will turtle back several thou whilst the poor primer repokes (a goofy contention but one easily tested for ;) ) then you show the driver, you give a step by step replay of the forces acting to effect this and we can make a movie.


BTW....... how does VA account for the FACT that it's common for primers to pop up and then, when the web yields, for the casehead to be driven back FLATTENING THE PRIMER instead of re-seating it? This is commonly cited as an illustration of why using "flattened primers" as an indicator of pressure is problematic.

al-NOTanengineer-inwa

MikeTheRock
11-01-2013, 11:50 PM
???

But silly people, slobbering chambers into rifle using "Go Gauges" have managed to bugger up enough rifles that a large segment of the competitive shooting population believes the 6X47L to be somehow "less accurate" than the Dasher....




Hi Alinwa,

I've been following this thread a bit as I'm having a 6.5x47 built and I was wondering if you could elaborate on the above quote a bit.

Also, you stated that "...it will never thin at all if one's dies are properly matched." What is your method for making sure ones dies are properly matched?

Thanks in advance,

Mike

alinwa
11-02-2013, 03:10 AM
Hi Alinwa,

I've been following this thread a bit as I'm having a 6.5x47 built and I was wondering if you could elaborate on the above quote a bit.

Also, you stated that "...it will never thin at all if one's dies are properly matched." What is your method for making sure ones dies are properly matched?

Thanks in advance,

Mike

The easiest way is to get a neck sizing setup ALA Wilson hand dies.....I most often just cobble something up these days because I can..... but you must do what you can to be able to reload some cases over and over without sizing. This is most often called "shooting "neck size only"" So you fire three cases over and over using moderately stiff loads and they will get progressively tighter and tighter. KEEP YOUR LUGS GREASED!!! At some point they'll become uncomfortably tight, like you have to use your palm to close the bolt. Put them into a ziplock.

Now fire some more cases until they're "moderately tight," like you have to use your thumb to close the bolt.

Now fire some more and stop when they're "perfect, just a little feel."


Send the six cases off to Neil Jones ( http://neiljones.com/ ) with a detailed explanation and you'll get back a die which will allow you to wear out a barrel using 20 cases......


Now, there are a host of other issues. For instance most chambers are too small, too tight and will develop a "click" at some point. Your fitted die won't fix this. But it WILL allow you to fire your cases over and over once you figure out how to use it.


If this works, here's a picture from another thread from years ago (YAYYY! Wilbur fixed the 'search' function!!!) which shows some cases that have been fired almost 50 times....

http://benchrest.com/showthread.php?58805-Al-s-6x47L

If the link doesn't go to pictures try scrolling around to find some snapshots

If NOT...... I tried :)

hth


al

alinwa
11-02-2013, 03:20 AM
Wow....


I just reread some of that old thread. A lot has changed since then, I was just testing a lot of the stuff mentioned. At the time of that thread the brass was pretty newly arrived in America. I bought from the first three shipments and still have lots of cases. But all of the assertions and testing have proven out.

mks
11-02-2013, 01:07 PM
This is the problem with Varmint Al and his cartoon guesses. Some of his assumptions are just WRONG :)

Which ones?


In the real world primers vary in their protrusion with some of them popping up 3-4thou, FAR BEYOND the springback of the brass, which in any case couldn't exceed a thou.

Everything deflects and springs back - the barrel, action, bolt and brass. The final primer protrusion is the product of all of these.



(Really, caseheads don't spring back at all but we'll leave that be for now)

Are you saying that the brass in the casehead somehow violates the laws of physics?



Now, you show me a mechanism for driving that silly phallic casehead story and I'll TEST IT...... if in FACT them pumped up caseheads will turtle back several thou whilst the poor primer repokes (a goofy contention but one easily tested for ;) ) then you show the driver, you give a step by step replay of the forces acting to effect this and we can make a movie.

The movie is already available on VarmintAl. I tried to explain the step-by-step in my last post. It boils down to the pressure late in the pressure pulse being sufficient to push the primer back out, even as the casehead is springing back. It makes sense, because if low pressure pops the primer out before the case head moves, then surely it can do the same thing after the casehead springs back.

As for experiments, one could use plastigage. If it gets squashed thinner than the final primer protrusion, then the primer must be getting pushed out again after the maximum case head deflection.



BTW....... how does VA account for the FACT that it's common for primers to pop up and then, when the web yields, for the casehead to be driven back FLATTENING THE PRIMER instead of re-seating it? This is commonly cited as an illustration of why using "flattened primers" as an indicator of pressure is problematic.

Watch the movie. It's easy to see that the corner of the primer is an area of stress concentration, which leads to flattening, particularly when the case head is driven outward after the primer. The effect is exaggerated in the right hand movie.

alinwa
11-02-2013, 04:44 PM
Which ones?

I'll reiterate two that have already been mentioned, #1, that the brass casehead can/will "recede" or draw back further than the boltface leaving the primer popped up and #2 that dragging weighted plates in any way equates to the interaction of the brass case to the chamber walls.



Everything deflects and springs back - the barrel, action, bolt and brass. The final primer protrusion is the product of all of these.

Of course, but anyone with even a basic understanding of springback realizes that they all exhibit different rates of same. I'll not waste time explaining the obvious differences. If you're not implicitly aware of the fact that the "lead slug deformation" of the casehead is different than the radial deformation and springback of the casebody I can't make you see it.




Are you saying that the brass in the casehead somehow violates the laws of physics?

No.......and therein lies the problem with VA's cartoons. It's the assumptions that are wrong, not the physics




.


I'm not going to go very far with this because I can't, politely. It's obvious you've never actually experienced primer popup, but if you do please ask yourself "WHY is the amount of protrusion directly related to the amount of headspace present?"

I'll not pick on Varmint Al, he simply doesn't model well. He misses the point most of the time.

But while you're at it, ask yourself "WHY can some setups show ZERO tendency toward casehead separation? Also ZERO case growth and ZERO primer popup, while others show one or all of these symptoms?" WHY can one guy fire a case 100 times at 70,000psi while the next guy has problems with moderate loads?"


Incidentally you're on the right track with the plastigauge but lead shot works even better. And gold foil makes a great gauge for comparing higher chamber pressures. And various tapes work well for establishing headspace testing parameters. And PLEASE DO do some testing!!


PLEASE!


It's the difference between reading a book and riding a bike.

alinwa
11-02-2013, 05:15 PM
Well, I lied. I am gonna' pick on Varmint Al, a liddle.

Please note that my aim IS NOT to "pick on Varmint AL," it's to illustrate my point which is, PLEASE PEOPLE, DO NOT ASSUME that because someone says something it's automatically true!


This stuff just slips by....


I find VA really hard to read because an awful lot of stuff is just "slipped in" as assumption and unless one has actually BUILT STUFF one can be led down a rosy path. In his modeling Al consistently states as fact that more highly polished chambers are more slippery and that "rough chambers" grip the case such that they're more likely to stick in place.


Please, will some of you (Keith :) ) take the time to check on this?? All you've got to do is spend a few hours playing with the finish inside your chamber. I've done this. I don't find smooth chambers to be more slippery........


And Keith, I found VA's simulations to show primers popping up and then being squished back into place once, crumpling the corners. This matches my own observations. True "popped up" primers still have rounded edges...... and when you remove the primers and reinsert the empty cases THEY STILL HAVE THE SAME HEADSPACE GAP AS BEFORE FIRING.

mks
11-03-2013, 01:33 PM
#1, that the brass casehead can/will "recede" or draw back further than the boltface leaving the primer popped up and #2 that dragging weighted plates in any way equates to the interaction of the brass case to the chamber walls.

Neither of these are assumptions. 1) The brass is modeled as an elastic/plastic material, which it is, and the recession of the case head is calculated by the laws of physics. 2) Al simulated a whole range of friction coefficients. Just pick the one you think is correct, and see if the simulated motion follows what you expect.

BTW, how would you quantify the friction coefficient? The weighted pull experiment is a straight-forward, low-budget approach, but its applicability to cartridge cases does depend on the linearity of the coefficient to higher loads. How would you do it?


Of course, but anyone with even a basic understanding of springback realizes that they all exhibit different rates of same. I'll not waste time explaining the obvious differences. If you're not implicitly aware of the fact that the "lead slug deformation" of the casehead is different than the radial deformation and springback of the casebody I can't make you see it.

Yes, of course, they have different rates. But to contend that brass acts like brass in the neck and body, but acts like lead in the case head, doesn't make sense. Caseheads deflect and spring back like brass, not like lead.


I'm not going to go very far with this because I can't, politely. It's obvious you've never actually experienced primer popup, but if you do please ask yourself "WHY is the amount of protrusion directly related to the amount of headspace present?"

Nah, we can be polite, cause this isn't personal, it's a discussion of the science. We are both looking for the truth, right?

There are two ways you can get primer protrusion: 1) Low pressure loads in which the casehead deflection is elastic, and comes short of the boltface. In this case the final casehead to boltface clearance (I think there are those who would argue against calling this headspace) is the same as the initial clearance, and the primer protrusion is proportional to that clearance. 2) High pressure loads in which casehead deflection is plastic. In this case, the final clearance is less than the initial clearance, and the primer protrusion is proportional to the final clearance, not the initial clearance.


But while you're at it, ask yourself "WHY can some setups show ZERO tendency toward casehead separation? Also ZERO case growth and ZERO primer popup, while others show one or all of these symptoms?" WHY can one guy fire a case 100 times at 70,000psi while the next guy has problems with moderate loads?"

By avoiding plastic deformation of the casehead, by using a stiff barrel, action and bolt, and low clearance. Your answer is the same, right?

The way we differ, it seems, is whether elastic deformation occurs. The unquestionable observation is that the case length is the same before and after firing. But what happens in between? Does it make sense that a case head exposed to 70 ksi doesn't move at all? I don't thinks so. It deflects and returns to the same length.

alinwa
11-03-2013, 06:55 PM
Neither of these are assumptions. 1) The brass is modeled as an elastic/plastic material, which it is, and the recession of the case head is calculated by the laws of physics. 2) Al simulated a whole range of friction coefficients. Just pick the one you think is correct, and see if the simulated motion follows what you expect.

I don't think anything about the modeling is correct although the last movie is closer to what actually happens. BTW at no point do I see where the primer cup re-protrudes. I must have missed that movie?

BTW, how would you quantify the friction coefficient? The weighted pull experiment is a straight-forward, low-budget approach, but its applicability to cartridge cases does depend on the linearity of the coefficient to higher loads. How would you do it?

I wouldn't attempt to "quantify" it, knowing from prior work that there is no linear relationship, nor is there a similarity between a block and a pressure-supported flexible casewall. I'd work with the much simpler criteria of "slide"/"no-slide."



Yes, of course, they have different rates. But to contend that brass acts like brass in the neck and body, but acts like lead in the case head, doesn't make sense. Caseheads deflect and spring back like brass, not like lead.

No, the difference is simple math. My "lead slug" analogy was an attempt at shortcutting a lengthy explanation about the ratios involved. Stretching the tube several thou in length over a very short section of the case VS stretching it a thou or two over the entire radial hoop of the case



Nah, we can be polite, cause this isn't personal, it's a discussion of the science. We are both looking for the truth, right?

There are two ways you can get primer protrusion: 1) Low pressure loads in which the casehead deflection is elastic, and comes short of the boltface. In this case the final casehead to boltface clearance (I think there are those who would argue against calling this headspace) is the same as the initial clearance, and the primer protrusion is proportional to that clearance. 2) High pressure loads in which casehead deflection is plastic. In this case, the final clearance is less than the initial clearance, and the primer protrusion is proportional to the final clearance, not the initial clearance.


I agree



By avoiding plastic deformation of the casehead, by using a stiff barrel, action and bolt, and low clearance. Your answer is the same, right?

The way we differ, it seems, is whether elastic deformation occurs. The unquestionable observation is that the case length is the same before and after firing. But what happens in between? Does it make sense that a case head exposed to 70 ksi doesn't move at all? I don't thinks so. It deflects and returns to the same length.


Here we diverge rather widely..... I've never observed an instance, not ONCE in many years of measuring cases where "the case length is the same before and after firing." So calling that an "unquestionable observation" on your part puts us well into the realm of differing opinions and even perhaps beyond it into "Have you ever actually DONE this???" This is what I meant about the polite part. I have to question this statement of "fact" and in my experience when I do this folks get mad and walk off........But I can't imagine that anyone who's actually measured for expansion would have found "the same case length before and after firing."

I kinda' agree with your last part......YES the entire system deflects and YES part of the answer is to keep clearances small and YES this is to minimize plastic deformation.........but MINIMIZE....... not eliminate. Yes, one can eliminate the problem of casehead separation by eliminating the stress riser at the web but one cannot keep from having to resize the cases. The only thing we don't resize for is casehead expansion, which is different than that of the entire rest of the case. Not only is the ratio wildly skewed (expansion of a thick disc of copper VS the thin hoop of the casewalls) but the pressure acting to expand the casehead isn't even in the same room with the pressure acting on the main casebody. In fact, caseheads wouldn't expand measurably AT ALL if it wasn't for the primer pocket and flashhole.

But I digress :)




we'll try for the "answers in bold above"

mks
11-04-2013, 12:13 PM
I don't think anything about the modeling is correct ...

I wouldn't attempt to "quantify" it (the friction coefficient)...


VarmintAl, if you are following this thread, I now understand why you haven't jumped into the discussion.;)
Alinwa, neither models nor experiments are perfect, but we can learn from both. By dismissing models, you are missing out on half of the pool of available knowledge.


I've never observed an instance, not ONCE in many years of measuring cases where "the case length is the same before and after firing." .


But from your previous post:

...the empty cases THEY STILL HAVE THE SAME HEADSPACE GAP AS BEFORE FIRING


It is the latter "observation" (yours) that I am not "questioning." If, in fact, they experienced no plastic deformation, this does not mean that they did not deform elastically. Regardless of how much plastic deformation occurs, spring back of the elastic part of the deformation provides a mechanism for primer protrusion to increase as the casehead recedes with the falling chamber pressure.

Cheers,
Keith

alinwa
11-04-2013, 05:45 PM
VarmintAl, if you are following this thread, I now understand why you haven't jumped into the discussion.;)
Alinwa, neither models nor experiments are perfect, but we can learn from both. By dismissing models, you are missing out on half of the pool of available knowledge.



But from your previous post:


It is the latter "observation" (yours) that I am not "questioning." If, in fact, they experienced no plastic deformation, this does not mean that they did not deform elastically. Regardless of how much plastic deformation occurs, spring back of the elastic part of the deformation provides a mechanism for primer protrusion to increase as the casehead recedes with the falling chamber pressure.

Cheers,
Keith

I dismiss this modeling because it's not relevant. In simple terms, real world cases DO NOT exhibit characteristics as predicted by this "modeling" session. Cases do not stick any better in rough chambers and the statements that they DO are evidently the result of not testing real-world because in firing rounds in real rifles it quickly becomes apparent that chamber finish has little to do with it.

I was unclear...... my term "THEY STILL HAVE THE SAME HEADSPACE GAP AS BEFORE FIRING" is incorrect...... they still have NEARLY the same headspace gap as before firing. Even when bouncing back elastically the cases do grow some at each hit.