Neck/Shoulder Sizing

Fired cases measure .254". That should make the chamber neck that size or .001" more so, .255". Loaded rounds measure .250". When using the Redding bushing die the bushing is .248".

this is not a custom rifle. It's a Sako Vixen L461 Heavy Barrel with beaver tail stock. It shoots good I just wanted to wring all the accuracy I could from it but now doubt I can shoot good enough to notice any difference in turning or not. My groups this past Tuesday ran .532-.221". I suppose for a factory rifle I should be pleased.

 
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One of the things that never seems to get mentioned in these threads is the reason WHY tight-necks/turned necks were invented. And there is a reason, not some esoteric thing like "concentricity" nor "consistency" nor "bullet release" (whatever THAT is!) but a real, valid REASON for turned necks. The neck of the case is what supports and guides the bullet as it's being HAMMERED into the lands with 600+ pounds of swirling buffeting hammerforce, the neck of the case is the GUIDING MEANS for this insertion, hence the neck clearance directly relates to the linearity of the insertion.

That's 600 POUNDS, not "psi" of some tender "pressure front," it takes 600lb of force, a 600lb WEIGHT on an iron rod to start the bullet. A jiggling, wiggling shaking and baking iron rod......

Bottom line......The bullet WILL be cocked over as much as the neck clearance allows.

WILL BE cocked over,

cannot help but be cocked.

That bullet ain't gonna' magickally float in the center of the hole while the 600lb monkey footstomps it into the rabbithole.

Hence fitted necks.

Something to consider.

al

BTW, groups is 5 shots.
 
Well, I must disagree.
The entire case holds the bullet in alignment. It's nice if the neck is also in concert.
Who can say that the neck hasn't expanded to the dimension of the chamber before that split second when the bullet is going, going, gone? The close proximity of case neck to chamber dimension has as much to do with brass movement and case longevity as it does with seating pressure uniformity and release inertia. Seating depth and contact with the lands also aids in bullet alignment with the barrel. It helps if Venus is in alignment with Cassiopeia.
 
ColColt said:
Fired cases measure .254". That should make the chamber neck that size or .001" more so, .255". Loaded rounds measure .250". When using the Redding bushing die the bushing is .248".

this is not a custom rifle. It's a Sako Vixen L461 Heavy Barrel with beaver tail stock. It shoots good I just wanted to wring all the accuracy I could from it but now doubt I can shoot good enough to notice any difference in turning or not. My groups this past Tuesday ran .532-.221". I suppose for a factory rifle I should be pleased.

Click to expand...

There's a good chance your rifle is shooting better than you think. Seems like we've had some of this discussion in the past, but are you using any kind of wind flags? A 5-7mph gust of wind that you don't see somewhere between you and the target could easily cause that flyer you are looking at. And of course, there are all sorts of gun handling issues that can comp0licate things. I can shoot a benchrest rifle fairly well on a good day, but I just sold a very accurate Sako 6PPC because I could not manage to get the hold right on the setup up to consistently shoot. The fault was not in the rifle.

Rick
 
That's a nice little group. Keep it up. Check out this site: http://www.tripledeuce.net/ .

Barrel, Bullet, Bedding is the old saw. If you aren't using great bullets, try some custom 22 bullets. You might check into getting it pillar bedded, if it isn't already.

Best regards,

Greg Jennings
 
The closest thing to wind flags we have are ribbons someone tied to the bottom of the frames at the 100 and 200 yard targets. There was a crosswind that day but not bad and not having a meter to check I could only go by what the weatherman reported that morning of 4-5 mph winds. I suspect more than that it was me that was off a bit on my sighting.

The only bullets I've tried have been several Sierra and Berger in the 52-53 gr range but have recently acquired some Sierra 50 gr Blitz bullets. Those are the better ones I know about.
 
Uthink Uknow said:
Well, I must disagree.
The entire case holds the bullet in alignment. It's nice if the neck is also in concert.
Who can say that the neck hasn't expanded to the dimension of the chamber before that split second when the bullet is going, going, gone? The close proximity of case neck to chamber dimension has as much to do with brass movement and case longevity as it does with seating pressure uniformity and release inertia. Seating depth and contact with the lands also aids in bullet alignment with the barrel. It helps if Venus is in alignment with Cassiopeia.
Click to expand...

LOL! You don't read so good does you Uthink

Who can say that the neck hasn't expanded to the dimension of the chamber before that split second when the bullet is going, going, gone?
Click to expand...

Well, I can, for one ;) state with certainty that the neck HAS expanded fully to seal before the bullet engraves....

And by the way, Wenus and Cassiopeia don't enter into it, I'm about what DOES happen, not about what "might" or "could" happen in this or some alternate reality......I'm about testing and measuring and about reading of others' testing and measuring. The ignition/pressure curve within the case is well understood, it's not a matter of alchemy nor guesswork..
 
ColColt said:
The closest thing to wind flags we have are ribbons someone tied to the bottom of the frames at the 100 and 200 yard targets. There was a crosswind that day but not bad and not having a meter to check I could only go by what the weatherman reported that morning of 4-5 mph winds. I suspect more than that it was me that was off a bit on my sighting.

The only bullets I've tried have been several Sierra and Berger in the 52-53 gr range but have recently acquired some Sierra 50 gr Blitz bullets. Those are the better ones I know about.
Click to expand...

It's pretty much impossible to get where you want to be without a decent set of wind flags. You might gain a bit with some custom match bullets, but flags are worth more than you will pay for them and good ones aren't exactly cheap. OTOH-anything is better than what you have.

Rick
 
FBecigneul said:
Splain to me how the bullet will be cockeyed if the case is aligned in the chamber provided the neck is not catty wampass and the brass isn't flexing like used bubble gum. The case is a tighter fit than the neck, remember. Add to that the fact that the bullet has to been sent on its way as the bullet seating tension is such that it, the bullet, is released with less resistance that that of brass stretching. While it is true that the neck expands and seals the "chamber" the true resistance doesn't begin until the bullet engages the barrel beyond the free bore.

I can't speak for the other guy who disagrees but, I think I read well and I absorb what is written by people more learned than you or me. I believe this subject is outside of your area of expertise.
Click to expand...

I don't know what a lot of this means, explains or implies (except the last part), but it seems to support my contention without meaning to.

Here's what DOES happen, unless your chamber is designed like a Weatherby or Edge.

#1-As pressure builds in the case the bullet slides forward to stop on the "leade" or tapered beginning of the lands..... or, in most accuracy situations it's already there. most bullets in accurate rigs are seated within a few thou of the lands.

#2-As pressure continues to build the case pops out, neck first to seal the chamber. This is it's primary function. If this function is compromised the results are dramatic. Some of us have actually experienced this, some of us can state with fair certainty that the neck DOES POP OUT TO SEAL because when it doesn't all sorts of cool stuff happens. Some of us have tested and observed that the smart guys who wrote the books were speaking truth.

#3-When the neck pops out to seal on a typical chamber, THE REAR OF THE BULLET IS STILL IN THE NECK. The last guiding support on the bullet is the neck...... not the body of the case or the headspace, the NECK. But the neck just LET GO....This leaves the base of the bullet unsupported.

The rest seems obvious. The bullet hasn't moved yet, the rear end is waggling in the breeze, the front end is butted up to the leade, trying to engage but needing 600lb of pressure to do so........ and it's just hanging there, unsupported, or it may have a section of freebore to "hold it in place."

But for those of you who, like FBecigneul, feel I'm unqualified to make these assertions please do some research. Start with Harold Vaughn's 'Rifle Accuracy Facts' and continue with Rinker's 'Understanding Firearms Ballistics' and finish up with Howell's 'Designing and Forming Custom Cartridges For Rifles and Handguns' and you'll have a fair understanding of what goes on.....

Beats guessing.

For those of you who want to TEST this stuff, do like I have...... buy reamers in sets of six with progressively larger necks, buy them with zero freebore and buy a bunch of throating reamers. I can help you with the design (diameter, leade angle, steps/angle changes if you want, I've tried up to three) and show you how to modify Kiff's throaters for hand-held use. Now with a few notebooks and a range of powders and bullets you can empirically TEST for what affects what.

Like I have.

Or, have guessers explain it to you, and then you can go "straighten cases" and spend lots of time and money on "concentricity" and such, spend your moneys however you want..... Or you can listen to someone who's actually SPENT tens of thousands of dollars on junk guesses. Someone who actually takes these guesses and tries them out....... and believe me a lot of the guesses I've spent money on are from Bench Rest Hall Of Fame builders and shooters. Being a BR shooter doesn't make anyone an expert on building stuff. There's no substitute for SPENDING THE MONEY. Somehow, spending thousands of dollars chasing people's pipe-guesses really brands the results into one's memory. Ask me sometime about the dollars I've spent trying to "contain caseheads" against expansion, the foolish garbage I've bought into attempting to "eliminate the click" until I just went out and did it. Or about buying into the theory that "sizing only half of the neck aids linearity". Or the theory that "cases blow out in the top side so indexing will help to"....blahh blahh blahhh... Ask about the numerous "case straighteners" I own...

But you'd better have a lot of time.

I've made cases and fitments so clean that you couldn't find runout anywhere and the guns shot like dung. And conversely, I now have rifles where you can just throw loads at them and they shoot like crazy.



I went out and bought a lathe because it was cheaper than paying for other people's guesses.

So please, some of you qualified guys explain for the op just how the body of the case "holds the bullet in alignment?" during the firing cycle....I can tell you how it DOESN'T, and if you want verification from a rocket scientist ask Harold Vaughn.

I have.

al
 
Al,
let me make one correction. Neither you nor I shoot as well as the fellows that have abandoned fitted necks for greater clearance that requires necks to be sized. I understand that for the 6PPC, that some of the best shooters are using closer to .003 than .002 for clearance. I am sure that this was just an unintentional oversight on your part, and that you really meant to extoll the virtue of tight neck chambers with controlled clearance, using turned necks.

As others have mentioned, for this shooter's situation, the first thing that is needed is a set of flags, and, if I may be so bold, encouragement to load at the range, because the load that shoots very well on one day, may require adjustment to do as well on another. I think that the sensible thing is to work on the areas that are most obvious first, and leave the finer points till after those are taken care of. To me that rifle, and the shooter show great potential. There is nothing wrong with the bullets that he is working with. Having a way to see how straight ammo is is a good way to gauge the quality of ones process, and equipment. Without it, one can be limited by something that one has no way to see.
 
Al Boyd has a point about neck clearance, I have been playing with .003 clearance with a .336 neck and have found for one I get better extraction can you tell me ,Am I doing the right thing? Everything seems to seal at the neck, no blow by on the shoulder. And another thing when the barrel had a .338 neck it wanted to shoot best at .125 off the lands and just touching with the .336 is it because maybe different in lead or throat. .338 lead-.137 .336 lead-226 But I know guys that haven't got to do anything special with their loads and shoot like crazy!
Throat.123 throat-.212

Joe Salt
 
I can say this...

Everybody thinks they are doing the best they can do. Whatever works for them at any time will remain in their process...likely forever. Even if it doesn't work for a barrel or two it very often doesn't hurt. We have to watch for the things that work in a specific barrel and don't work well in other barrels. Said differently, what has always worked may not work now and we have to try that stuff that didn't work before. In any case, the barrel will be worn out sooner than later and we have to start over.

Some barrels are just better than others. Some rifles are just better than others. Some folks have more money than others.
 
OK Boyd, Joe and others.....2 things. First of all try more than .003 sometime, like factory chambers etc. This IS why the founders of BR turned necks, to make the old Sako brass round, to keep the bullets straight in the bore. It's all been recorded. Nowadays we just do a lot of stuff "like it's always been done" considering .003 total clearance to be "loose" but it ain't. In fact there are people trying it all the time, general concensus is that groups start to open up as you pass .003 total (.0015/side)...And secondly, the bullet IS cocked over by however much the neck allows. It has no choice BUT to be. This isn't arguable. There are various ways to fix this, to straighten the bullets out. The two most common being long and tightly fitted freebore and long and parallel bullets, bullets with long bearing surface.

My point is simply that all the "straightness" in the world as applied to the cartridge case, does nothing to keep the bullet straight when you've a sloppy neck.

Cartridge fit does have a big effect on vibration, another leading cause of dispersion.

As far as better extraction and neck size. interesting.... I can't imagine any relationship between the two and certainly haven't experienced it :) And I have 30cal chamberings with necks almost an inch long. I've a 50cal project where the entire case is parallell and the neck is over an inch long. I've never found any extraction drag.

al
 
Speaking of cartridge straightness, I looked at a Hornady Concentricity Gauge that looks to be just the ticket for checking and even correcting any run out. The one question in my mind about it was what are you really doing to the neck when you use the screw to push the bullet if you want to straighten things up. Mind you, you're only talking about maybe a couple thousandths.I don't know about that but, it looks like a good tool.
 
I think that the best use for concentricity gauges is to diagnose equipment problems, with an eye toward modifying, replacing, or changing how you use equipment. I think that the Hornady misses the boat in one significant way. It supports the back of the case off of the rim, and after firing, particularly in a factory chamber, the body of the is most likely not going to be concentric with the rim. If you want to straighten, and I am not saying that you should, IMO the H&H gauge (search on accurateshooter.com) is a much better choice. For looking at cases and loaded ammo, the Sinclair works pretty well.
 
Anybody ever spin the loaded rounds and measure runout?

About 30 years ago I went through a phase of measuring the bullet runout of all my loaded rounds on a V-Block with a thousandth reading dial indicator very near the tip. I rolled all my ammunition and segregated it in the box by runout . I shot .001", .002" , and if needed .003" rounds on the record target and all the higher runout shells were shot on the sighter. I did this for about 1/2 a shooting season and it proved only one thing to me beyond a shadow of doubt. High runout rounds shoot fantastic as sighters !
 
Given that you have a straight chamber, including the neck area, 60,000+psi of pressure will make it all straight. Again, given that your die and your seater die are straight, I see no reason to use a concentricity gauge. Your dies will keep you on the straight and narrow. See if you can borrow one or have a seasoned BR shooter help you in checking that stuff. I have one here gathering dust. I have a very capable BR smith and when I go there I take stuff over there to check it. I see no reason to straighten anything out after the first couple firings. I think I saw that you are in eastern Tennessee and there are a bunch there. There is no need to over think this stuff. Look for a tutor in your area. There are lurk ears on this sight who may have already seen your plight.
 
That was a good read about the H&H gauge and the comments seemed to be quite varied and controversial.

I can only assume that my sizing die(Redding Bushing Die) and seater die(Forster BR Seater) are straight. I don't know of any BR shooters around here although I'm sure there are. There are no BR matches that I know of at the Oak Ridge range. I'd go to them if they did. All I know they have are muzzle loading competition, CMP competition and the like.
 
ColColt said:
That was a good read about the H&H gauge and the comments seemed to be quite varied and controversial.

I can only assume that my sizing die(Redding Bushing Die) and seater die(Forster BR Seater) are straight. I don't know of any BR shooters around here although I'm sure there are. There are no BR matches that I know of at the Oak Ridge range. I'd go to them if they did. All I know they have are muzzle loading competition, CMP competition and the like.
Click to expand...

Few of us who compete in any kind of benchrest have ranges ta our back door (unless we have our own personal, private range). If you are near Oak Ridge you are within two hours of monthly matches at Jonesville VA, Somerset KY and Gallatin TN. You would be welcome at all.

Rick
 
My remarks were not to say that you should go right out and get one, more that if you decide to, I wouldn't choose the one that you mentioned.
 
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