Turning Brass During Its Life

A

abintx

Guest
A lot of top competitors have advocated turning necks so that there is a total clearance of .0015" (.00075" on each side) between the case neck and the chamber wall.

Since this clearance is extremely small it would seem reasonable to monitor this clearance during reloading because brass flows forward.

My questions are:

1. Do you monitor brass flow for an increase in neck wall thickness?

2. How often have you found it necessary to turn necks, beyond the initial turn, to maintain the .0015" clearance?

Thanks for your response.

Art
 
Turn your brass

abintx said:
A lot of top competitors have advocated turning necks so that there is a total clearance of .0015" (.00075" on each side) between the case neck and the chamber wall.

Since this clearance is extremely small it would seem reasonable to monitor this clearance during reloading because brass flows forward.

My questions are:

1. Do you monitor brass flow for an increase in neck wall thickness?

2. How often have you found it necessary to turn necks, beyond the initial turn, to maintain the .0015" clearance?

Thanks for your response.

Art
Click to expand...

once (prior to fireform) ( by what ever method you wish), and shoot. If you think you have to turn it again, it is time to throw it away and get new. Or your initial process is suspect. Whether it is 6PPC or 30x44 or 30BR, your initial neck turn should be enuf for the usable life of the brass. If you are getting donuts, you need to look at teh process you use for the first turning process. Or start using a cutting mandrel. And you STILL need to examine your case turning process
 
For one, brass doesn't 'flow' anywhere.
Cases can lengthen with firing for a handful of reasons; High body taper, low shoulder angle, oil in the chamber, excess headspace, excess pressure.
These things should be considered.
For instance, if you're using a cartridge known to need constant trimming, maybe you shouldnt go tight neck or turn with it.
 
David and Mike ...

Thanks for your comments. My initial turning process yields loaded rounds that measure .2605 for a .262 6PPC neck.

Does anyone have an answer to my questions ???
 
Tim ...

tim said:
The necks won't change.
Click to expand...

I know of a previous Super Shoot winner who has also been a member of the USA World Benchrest team who monitors his brass for this change. My questions were posed to see who else may have been aware of this progression and also monitored it. I was looking to see how prevalent the practice is. :)
 
Hi Art.
I monitor my neck thickness regularly using Redding neck bushings over a loaded round as a quick & easy 'go/no-go' guage. I've found a few snug ones this way..not all on my own rifles, either. ;)

One thing I've noticed about the Redding bushings: a .3270 neck diameter (over the pressure ring of a seated bullet) won't take my .327 Redding bushing...I need the .328 Redding bushing. Checking my bushings with pin guages confirms they run about .001 smaller than the stamped size, at least on my .30 cal. bushings.

For what it's worth. :) -Al
 
Art...

...are you asking about this because you're actually seeing your case necks get larger in diameter? If so, where? My guess is that it is only on the base of the neck, near the neck/shoulder junction...
I don't disagree with David...maybe you should take a look at your neck turning process; BUT, I'll offer another idea in the meantime. I push my shoulders back about .025" before I ever turn my cases. By pushing them back .025", I don't have to be real fussy about cutting into the neck/shoulder junction...just cut them back as far as the straight section of your neck goes and shoot. The end of the cut will end up somewhere on the shoulder after they've been fire-formed. Occasionally, I get a little bit of a donut if a virgin case was a little bit longer than normal. Rather than change my tools all around to recut the outside of the neck...(remember, the length of your cut has to change because the original .220 Russian case has now become a sharp shouldered PPC)...I have two Wilson inside neck reamers, a .243 and a .244. Wilson will make them custom sized to whatever you want. I use them on fired cases...when the neck walls are straightest...and take out what sliver of a donut there may be. Works GREAT!... As far as how often does it need to be done?...you might check them every 10-12 firings. If something is showing up quicker than that, you have other, BIGGER problems...
 
abintx said:
A lot of top competitors have advocated turning necks so that there is a total clearance of .0015" (.00075" on each side) between the case neck and the chamber wall.

Since this clearance is extremely small it would seem reasonable to monitor this clearance during reloading because brass flows forward.

My questions are:

1. Do you monitor brass flow for an increase in neck wall thickness?

2. How often have you found it necessary to turn necks, beyond the initial turn, to maintain the .0015" clearance?

Thanks for your response.

Art
Click to expand...

#1, yes

#2, never, it does not change except that necks get THINNER with age.


-----------------------------------------------

And I use clearances down to "0", scuff fit.

And I fire my rifles at ELEVATED pressures, just short of case failure.

And I expect my cases to last 50-100 firings or until I screw up.

I do this by spending money on fitted dies and by knowing how to use them.

You cannot do this with anything BUT fitted dies and the requisite knowledge.

al
 
al ...

alinwa said:
I use clearances down to "0", scuff fit. al
Click to expand...

Since you're still breathing, somehow the bullet is being released. Where is the release of tension coming from ???

What do you feel you've gained in accuracy by surpassing the old tight fitting necks used some 20 years ago [.0005" total; .00025" on each side] ???

Do you feel confident that you've left yourself some room for error, Safety wise ???

Getting many fliers ???

Make any changes when you change bullets ??? :)
 
alinwa said:
#2, never, it does not change except that necks get THINNER with age. al
Click to expand...

What accounts for the older necks getting thinner when Al Nyhus and Billy Stevens seem to be monitoring for thicker necks ???

Do necks get thin when fire forming, get thicker with renewed firing, and then thin again with prolonged use ???

What's the life cycle of a neck ???

--------------------------------------------------------------------

"Hi Art. I monitor my neck thickness regularly using Redding neck bushings over a loaded round as a quick & easy “go/no-go” gauge. I've found a few snug ones this way … not all on my own rifles, either." Al Nyhus

"I use Lapua brass and cut it to .0088 for a 6PPC with .262 neck which gives me just under .001 clearance on bullets with a .2435 pressure ring. I don't run into any problems if I keep the necks clean and occasionally check to ensure that I maintain at least .0005 as the necks grow from the brass flowing forward from firing. I only use a set of brass for about three matches and them trade them in for some new ones. I shoot V133 powder with the PPC and like to use a .257 button which will give a fairly heavy neck tension with the above setup. For me, V133 will not shoot as well unless you have heavy neck tension." Billy Stevens

Both quoted sources from Benchrest Central. :)
 
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Like Al, I've run with ~zero clearance on necks for one of my cartridges. It works fine, but like anything has to be managed.
You turn to a specific value based on measured bullets and chamber neck. The value measured on loaded rounds will not be a crap shoot. It is exactly where you put it, and pretty much remains so. You size for the tension desired, and that's what it is. For example, if it takes 60psi to overcome seating friction, it'll take a about that to release.

I didn't have any problems with it, and found that running like this, I didn't need to resize necks very often. In fact, until shoulders needed bumped(~4th reload for me), I could reload between shots with no sizing at all.

So all I'm saying I guess, is that it can be done without issues if someone chooses to do it. But they have to be the type of person who manages details.
Most shooters focus elsewhere. Other details..
Some weigh bullets. I don't piss around with it, but I measure every formed case capacity..

We all have our thing
 
mikecr ...

What brand and tools are using to turn, measure, and calibrate, so that you achieve and maintain the ultra fine tolerances you are working with ??? Can you list them for us ??? :)
 
I use Sinclair tools across the board. Turner/expanders, neck mic, caliper, runout indicator..
The cartridge is a 6.5wssm that took 3 turns to get where it should have been to begin with. My chambers and dies were cut with my reamer set.
My brass was in-hand, culled, & prepped before I ordered from Kiff. The finished barrels produced no surprises, and the brass was a perfect fit as expected. So were my dies.
I've fired 80 cases through 2 barrels now, without so much as a single annealing(beyond initial).
The brass is still exactly where I put it, preaccounting for fully fireformed dimensions. No surprises.

It seems you expect wide confirmation of a problem rare with benchrest cartridges. Atleast a couple of us haven't seen it, and provided contrasting examples.

Now,, from your perspective(not someone elses);
Why would brass get thicker? Where would it come from? How would unmelted metal flow? Do you think Al could run his clearance for so long if it did?
 
mikecr ...

mikecr said:
Why would brass get thicker? Where would it come from? How would unmelted metal flow?
Click to expand...

I'm not a metalurgist. I opened the thread as you recall with questions, not answers. I'm posing questions with the purposes of trying to learn something from the contentions of others with opposing points of view.

Tomorrow I'll call of my gunsmith, Super Shoot winner, and member of the USA World Benchrest team, Billy Stevens, and ask him why he does the things that he does and the thought process behind it.

In the meantime, perhaps you can explain why you believe that brass doesn't flow, and those that do, can provide the readership with their explanation of why they think it does and the safety considerations one needs to think about when working with extremely small tolerances. And, in the long run the rest of us might learn something from both schools of thought.

I'm looking for strong rationale to make me a believer in one theory or the other. Thanks for your involvement. :)
 
BRASS DOES NOT FLOW FROM FIRING!!!!! ....... I don't care WHAT Colonel Billy sez!


This old saw has been repeated for YEARS because folks get extra brass in their necks and even have to retrim them to length! The brass didn't "flow" there, it was PUSHED there by the act of resizing.

If brass "flowed" my cases would look like swiss cheese.

50 reloads, NO TRIMMING and NO FATNESS..... anyone can do it. The life cycle of the neck is several hundred reloads provided you set up for it.

The reason necks get thinner over time is simple abrasion, wear.... And because I often use BBS for sizing lube. I clean the necks with it and leave it wet to size. I'm not advocating this practice, just stating fact. For it to work you must have a HARDENED and fitted resizing die.

This die cannot be ordered from any production maker, it must be specifically fitted to YOUR chamber.

Now, let me make myself perfectly clear.... IF you do not understand the parameters involved and IF you don't have the requisite tooling for MEASURING changes, DON'T DO IT!!!


THIS statement puzzles me. "Since you're still breathing, somehow the bullet is being released. Where is the release of tension coming from ???" WHAT "release of tension?" You pushed the bullet into the neck with moderate pressure...... what has to be "released?" Why not just let the powder charge push it back out?

What do you feel you've gained in accuracy by surpassing the old tight fitting necks used some 20 years ago [.0005" total; .00025" on each side] ??? The fitted necks used 20yrs ago were NOT using .005 clearance...more like .001 clearance. I still shoot 'em quite a bit. I use the minimal clearance necks only for boattail VLD style bullets because they don't normally have a pressure ring. I feel confident that I could SHOW you the difference between scuff and .004 on any given day, therefore reason tells me that there's a degradation in accuracy when going from minimal to say .003 even though I may not see it. I actually normally shoot around .001 clearance.

Do you feel confident that you've left yourself some room for error, Safety wise ??? Absolutely, I'm The Safety Geek....... if I felt there was any danger I'd quit it.

Getting many fliers ??? Not with VLD's, in fact the opposite. With FB short bullets like 68gr 6mm's and 112gr 30's there's a large body of anecdotal evidence which suggests that too-tight clearance will cause fliers. I haven't experienced this myself. I have fired quite a few FB bullets w/pressure ring using clearances under a thou.

Make any changes when you change bullets ??? Of course. EVERY change requires scrupulous reassessment. This is just de rigeur.


al
 
Minimal resizing does help with brass 'flow', no doubt about it. When you physically make a case smaller in diameter, the brass has to go somewhere. Many times you can measure the difference in the case head-to-shoulder dimension as the case body gets smaller during sizing...the case gets progressively longer until the case shoulder finally contacts the shoulder in the die and you get your 'shoulder bump'.

The problem with minimal sizing is it's often not practical in real-world BR shooting. When the clock is running and the flags are dancing ...that's no time to be struggling with your gun in the bags due to minimally resized cases, a poor fit between chamber/die or any other cause.

When I find a neck that's getting a bit snug, I wrap a bit of worn 400 gr. paper tightly around the neck (with the bullet seated), give it a couple of turns and recheck it with my neck bushing go-no-go method until it's where I want it.

Not exactly high tech....:eek: :D
 
From my experience

Let me qualify this up front; I own one 6 PPC barrel but have never fired it. I have been shooting 30 cal rifles in competition for 11 years or so. I have been shooting 30 BR rifles for 9 or 10 years. During all of this time I have experienced all of my case necks growing in both length and thickness. I have to both trim them to length and turn them when they get too thick. I use them until the necks break off them or I do something dumb to distort them too badly to use.

Unlike most folks, I don't place much relevence on or in brass in general. I simply consider it a container to place the things that truly matter into. They will last a very long time if they aren't pushed too hard and are annealed properly and frequently, from my experience. ;)

I am a believer in the "Flow" deal though. How else do they get longer and thicker? I visuilize brass sort of like Spruce Gum. When one pulls it off the tree it's nearly rock hard but after it hits the 98.6 in a lads mouth it gets soft and flows into GUM to chew with a lovely bitter flavor. I visuilize brass doing something like that for the instant that big fire is lit and burns. Take your Spruce Gum out and stick it on your bed post overnight and it will harden up again but won't be in the same shape it was when you picked it off the tree. ;)
 
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