Shoulder Bump for Headspace

[Annihilator]

I am new to this forum but have visited often searching for answers. The first photo is of my Wilson Case Gage with no round inserted. The second photo is of a once fired case inserted into the case gage. The second photo shows that the fired cartridge is roughly .006 above recommended SAMMI max. The cases are from new Hornady .223 factory ammunition fired from my AR-15. I checked the head space prior to firing and they were all roughly -.002 below max.
Am I correct to assume that to prolong case life I should adjust my sizing die to bump the shoulders back no more than .004 even though this is above the recommended max? My reloading procedure is to use a Redding body die followed by a Lee neck sizing collet die. I got approximately the same reading on all 50 cases that I checked.
I generally get the same +.006 on rounds fired from my Mini-14.

 

[Walkalong]

For .223 for my AR and Mini 14 I just size cases to fit my Wilson gauge. (I now have a Sheridan as well, but only had the Wilson when I set up the sizer.) I get great case life. They usually get loose primer pockets after 8 to 10 or more firings and get scrapped, with no internal signs of case head separation.

For 300 BLK in my AR I set up the sizer to move the shoulder on fired cases an average .003. I use a home made "gauge" for this. This is also working well.

Welcome to THR

 

[Blue68f100]

You will need to bump the shoulder back till it fits the test gauge. Which means a min of 0.006". The Wilson gauge has a slot that will give you a 0.005 from min. As long as it's between the min -max your good to go.

My min spec 223R Chamber I only have to push it back 0.003". But my Wydle Chamber it's closer to 0.008".

 

[Rule3]

For your semi auto AR you would be better to full length size the brass then use the gauge per instructions to determine your dies are set correctly .

Even though the gauge will check case length it is much easier to just use calipers. Then trim if needed.

I see no need to mess with a actual height gauge?. Just use a straight edge over the top (like your caliper)

All explained in the destructions.

http://www.lewilson.com/images/CaseGages.pdf

 

[243winxb]

Head to datum measurements

Will the fired brass, when placed back into the rifles, let the action close fully? Some actions may open to soon, letting the brass stretch longer than the actual chamber size. This is when measured head to datum using a comparator. I find a comparator more useful than a Wilson type gauge.

[/URL][/IMG] http://www.hornady.com/ammunition/superformance-in-gas-operated-firearms

the gun is still in the process or firing while it’s trying to extract the cartridge case.

The sizing needed , may be different between your 2 rifles?

 

[fguffey]

Even though the gauge will check case length it is much easier to just use calipers. Then trim if needed.

It is about this time the instructions become destructions. The OP is measuring case head protrusion from the gage. Case head protrusion measure the length of the case from the datum/shoulder to the case head. If the OP was measuring the case for trimming he would measure the amount of neck protrusion from the case gage. The Wilson case gage measures from 'THE DATUM' to the end of the neck and from 'THE DATUM' to the case head.

I see no need to mess with a actual height gauge?.

In my opinion he needs to work on zeroing the height gage. And then there is the straight edge, in the old days Wilson made it clear the pocket rule could be used as a straight edge. I took it one step further, I added the feeler gage. And then there is the flat surface, everyone has got to have one, I have lay-out tables and set-up tables. I stand a case on a flat surface then place the Wilson case gage over the case and then go straight for the feeler gage. I check the gap between the base of the Wilson gage and flat surface.

And then there is that flaw when measuring the length of the case from the end of the neck to the head of the case; reloaders assume. I don't, I have one chamber that has an additional .016" added to the length of the chamber from the shoulder to the bolt face. When I size cases for that chamber I adjust the die off the shell holder .014"; that give me the magic .002" clearance.

And then when it comes to trimming; reloaders forget the additional .014" of added chamber length when measuring the case length. If they are not thinking they trim the additional .014" case length. Not me; I want my cases to cover the chamber.

F. Guffey

 

[243winxb]

Neck tension / bullet pull - Auto Loaders

Lee neck sizing collet die

On seating a bullet, the neck should expand a minimum of .002" for good bullet hold. http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm From Sierra. See "neck tension "

 

[Rule3]

The Wilson gauge is 1.760 from high ledge to high ledge

Measuring it again with some other device is a waste of time?

Yes ,it measures from the datum line but if it is not sized correctly or not on a FLAT surface it is also a waste. It has two ends for a reason.

It also will not work correctly if it is not clean out from oil or lube inside or if the case has crud on it,

No need to make it more complicated than need be.

 

[Bart B.]

If best case life and accuracy are your priorities for semiautos, full length sized fired cases such that their shoulder's moved back about .003". Forget case gauges such as those made by Wilson. .002" shoulder setback is ok for bolt guns.

Brass work hardens with changing its shape too much. Minimize it and all's fine. Doesn't matter what your chamber headspace is; adapt your methods for what you have.

I find that link 243winxb posted on Sierra Bullets information very interesting. It says neck only sizing is preferred by accuracy minded folks, yet Sierra has full length sized all their cases used to test bullets for accuracy since the 1950's. Benchrest folks finally gave up on neck only sizing not long ago; their smallest groups stayed the same size, but their largest ones got smaller.

 

[fguffey]

Benchrest folks finally gave up on neck only sizing not long ago; their smallest groups stayed the same size, but their largest ones got smaller.

I have never found a bench rester that could tell me the difference in case diminutions between a neck sized case and a full length sized case. And then there is that other part: the bench rester 'folks' never give credit to the builder of the rifle with one exception.

http://bulletin.accurateshooter.com/2009/05/ken-brucklacher-sets-1000-yard-score-record-100-8x/

It was about this time bench resters claimed all a bench rester had to do was do the same as Ken did. He had a rifle built and then he purchased case and did not prep the cases, he went straight to loading them and then won. He did not measure the chamber, he did not measure the cases. He did not measure before and again after. We do not know if the cases stretched from the shoulder to the case head .002" or .020". And no one knows what difference the .018" would have made on the accuracy.

But there you have it: All you have to do is etc..

F. Guffey

 

[murf]

case hardness all the same, everything else different on that norma brass. makes for consistent neck tension.

murf

 

[Bart B.]

I remembered that small 5-shot group fired with new, unprepped .300 Wby Mag cases when I was looking at my plot of two 15-shot groups fired atop each other at 1000 yards some years earlier:



The 190's were shot from once fired cases only neck turned then full length sized. The 200's were shot from new cases. First shot a 190, then a 200, then a 190 and so on to see how each would perform over 30 shots.

Both load's groups were under 5 inches extreme spread as measured in the pits. X-ring's 10 inches diameter.

People have been winning long range matches with new, unprepped belted cases since the 1950's.

 

[fguffey]

People have been winning long range matches with new, unprepped belted cases since the 1950's. Ken set the record with brand new Norma brass with no case prep whatsoever. He didn’t touch the flash holes or primer pockets — in fact Ken didn’t even chamfer the case mouths. This was brand new brass, not fire-formed. According to Ken, he “just added a primer, filled the cases with powder, and shoved in a bullet.”

I should not find it necessary to quote a quote furnished in a link but ???

People have been winning long range matches with new, unprepped belted cases since the 1950's.

Back to the quote to the link;

Brucklacher used Norma .300 Weatherby brass “right out of the box”. You read that right… Ken set the record with brand new Norma brass with no case prep whatsoever. He didn’t touch the flash holes or primer pockets — in fact Ken didn’t even chamfer the case mouths. This was brand new brass, not fire-formed. According to Ken, he “just added a primer, filled the cases with powder, and shoved in a bullet.”

Why all the drama with:

You read that right…

Seems it went from :"talk it to death": to "all you got to is load-um".

And the rifle has a nice pedigree with an aluminum stock but the rifle must not have cost much because the price was not mentioned.

F. Guffey

 

[Walkalong]

And then there is that other part: the bench rester 'folks' never give credit to the builder of the rifle with one exception.

This shows how little you know about the sport. When you fill out the entry form for a match one of the things asked is the gunsmith. They do indeed get credit.

But can we get back on topic please?

 

[FLIGHT762]

My various 5.56 NATO chambered AR rifles will push the case shoulders +.006"-.007". My WOA Wilde barrel pushes the shoulders +.005". I set my die to F/L to the bottom step of a case gauge which is @ 1.464"(SAAMI min.).

I want 100% reliability. I get good case life and I do not get case head separations bumping my cases to 1.464". Usually primer pockets give out before the case does.

If you want to check what your rifle will actually chamber, you can make some dummy rounds (with a seated bullet but no primer or powder) with various shoulder set backs and see exactly what that rifle's minimum bump length to chamber reliability would be. You can then set your F/L die with that measurement. I've done it with my rifles.

 

[Annihilator]

I’d like to thank everyone for your response and special thanks to 243winxb and FLIGHT762. The attached photos show a once fired case at +.006 (photo 1). Inserting the case into the chamber shows an out of battery condition (photo 2) when the bolt is slowly closed. This may be exaggerated by the tension of the extractor pin. The bolt will fully close when utilizing the bolt release and the force of the buffer and buffer spring. Measuring the case after this operation indicated that the shoulders have been bumped back to +.005. I believe this confirms 243winxb’s theory that the action may be opening too soon allowing the brass to stretch longer than the chamber. The barrel is a stainless .223 WYLDE 18” DMR with a rifle length gas system. I will also take the advice of FLIGHT762 and fabricate some dummy rounds. I may take that a step further and remove the extractor and slowly close the bolt.

As stated, this was my first post and I should have placed this in the reloading forum (my bad). As for those that are unfamiliar with a Redding Body Die, it full length sizes the case and bumps the shoulders back. The case neck is untouched for additional processing. As to the accuracy of my comparator, the granite base is ground and polished to .0001. The Wilson case gauge is close to surgically clean. I could probably eliminate the comparator by sliding a stick across the top of the case gauge, but these 66 year old eyes are no longer able to distinguish if the light shining through the crack of the stick is .001 or .002. How we progressed from once fired .223 brass to unfired belted magnums is quite beyond me.

______________________________________

USN (1967 – 1971) Inshore Undersea Warfare Group 1, Unit 1, Republic of Vietnam

 

[fguffey]

This shows how little you know about the sport. When you fill out the entry form for a match one of the things asked is the gunsmith. They do indeed get credit.

http://bulletin.accurateshooter.com/...record-100-8x/

The above link list the builder, manufacturer of the action and barrel. The question was about the cost and then there was the time frame. Seems the writer of the article included the term "you read that right" meaning he thought that would come as a surprise.

F. Guffey

 

[Walkalong]

Link is bad.

But regardless, they list the smith and everyone knows who is smithing winning rifles.

 

[fguffey]

http://bulletin.accurateshooter.com/2009/05/ken-brucklacher-sets-1000-yard-score-record-100-8x/

I give credit to the builder, I want to know how much the rifle cost. Bench resters say all a reloader has to do is full length size and they have been doing it for years and years. I want to know the difference in the length of the chamber from the shoulder to the bolt face in a bench rest rifle, I want to know the length of the cases from the shoulder to the case head.

I have no interest in the number of years bench resters have been full length sizing, I want to know if there is one that can measure the length of the chamber from the shoulder to the bolt face and I want to know if there is a bench rester that can measure the length of the case from the shoulder to the case head.

I have no problem given credit to the builder, I posted the link; but I do not believe "all a bench rester has to do if full length size" does not come close to telling the whole story.

F. Guffey

 

[Walkalong]

I posted the link; but I do not believe "all a bench rester has to do if full length size" does not come close to telling the whole story.

Well neither do I, but that is public record as many times as I have posted about reloading for Benchrest. I also get tired of you always deriding "reloaders" and accusing them all of being ignorant and incompetent. If a fellow believed you they would think you are the only one in the world who can use tools to measure things.

Instead of telling us how ignorant we are, how about sharing your knowledge in a clear, concise, way instead of cryptoquotes.

 

[Reloadron]

Well neither do I, but that is public record as many times as I have posted about reloading for Benchrest. I also get tired of you always deriding "reloaders" and accusing them all of being ignorant and incompetent. If a fellow believed you they would think you are the only one in the world who can use tools to measure things.

Instead of telling us how ignorant we are, how about sharing your knowledge in a clear, concise, way instead of cryptoquotes.

Anymore I just overlook the insults. Reloaders this and reloaders that, amazing my loads and rifles work at all.

Ron