Everybody's favorite topic - case head separation

barnfrog · Dec 1, 2021

So I finally encountered my first instance of the dreaded CHS. I've been worried about missing the signs, but as soon as I saw the ring it was obvious.

The bent paper clip test was also quite obvious, so it was fortunate to get some first-hand experience with seeing and feeling the signs without any inconvenience or injury to anyone.

These are Winchester cases in .243 caliber that were loaded with 42.2 grains of IMR4350 and Barnes 80 grain TTSX bullets.

The thing that concerns me is that this was the first reload of these cases. They were factory ammo fired once in my Winchester XPR, full length sized, loaded as specified above and then fired in a Rossi single shot my friend purchased for his daughter. That powder charge isn't particularly hot according to Barnes. The data I have shows starting load level being 42.0 grains, max is 46.0.

I'm thinking the Rossi probably has too much headspace. It's definitely got more than my gun. Using the same comparator to measure base to shoulder, cases fired in the Rossi are up to 0.008" longer than those run through the Winchester. I'm going to order a no-go gauge and maybe a field length gauge as well and see what they indicate. I'm also going to cut open a couple cases from the same batch that don't have the ring and see if they show interior signs of stretching.

In the meantime, should my friend be worried about firing anything but factory ammo in this gun? If I were to start with virgin brass and load them only for his gun would we get more reloads out of them, or is this gun probably going to stretch cases no matter what?

AJC1 · Dec 1, 2021

Those guages aren't cheap and having go, no go and some masking tape should be more than enough. The field guage has about no use and the money would be better spent on the rcbs precision mic.

denton · Dec 1, 2021

Either use the Lee collet die, or set your full length die so that you only bump the shoulder back a thousandth or two, and it will be fine.

Walkalong · Dec 1, 2021

barnfrog said:
The thing that concerns me is that this was the first reload of these cases

Either the gun has a mechanical headspace issue, or the shoulders were moved back to far causing excess head clearance, which has the same effect as a properly sized case in an action with improper (excess) headspace.

243winxb · Dec 1, 2021

Buy a field gauge, if you must. Dont use same brass in both guns.

barnfrog said:
cases fired in the Rossi are up to 0.008" longer

How much longer then factory new ammo?
Buy new factory ammo for this gun only. Test fire rounds, measure head to datum. Size brass to same. Should stop separations?

Swampman · Dec 1, 2021

Walkalong said:
Either the gun has a mechanical headspace issue, or the shoulders were moved back to far causing excess head clearance, which has the same effect as a properly sized case in an action with proper headspace.

I'm not sure I understand.
Isn't "a properly sized case in an action with proper headspace" a good thing?

Steve in Allentown · Dec 1, 2021

barnfrog said:
They were factory ammo fired once in my Winchester XPR, full length sized, loaded as specified above and then fired in a Rossi single shot . . .

I agree with @243winxb that you shouldn't use the same brass in both rifles.

For what it's worth, I have separate buckets of brass for each rifle of the same caliber. The buckets are labeled to identify the specific rifle with each each bucket is associated.

I sacrifice nine pieces of brass for each caliber that cover a range of headspace in .001" increments above and below the SAMMI spec for that caliber. Each of these cases is labeled and I use them as headspace gauges. It takes time and effort at the press to get these cases sized perfectly but it gives me a quick and foolproof way of determining how much shoulder bump a specific rifle needs to get the amount of headspace I want on the brass.

I disassemble the bolt, place one of my homemade gauges in the chamber, and slowly close the bolt to see if it will just close with no resistance. I apply no pressure during the procedure. I will continue this until I find the one gauge that fits the chamber perfectly. Then for a bolt or single shot rifle I'll subtract .002" from the base to datum length of that gauge and that will be the sized length of the cases for that rifle. For semi-autos I'll subtract .004".

Walkalong · Dec 2, 2021

Swampman said:
I'm not sure I understand.
Isn't "a properly sized case in an action with proper headspace" a good thing?

Yes, I'll fix that, thanks.

jmorris · Dec 2, 2021

barnfrog said:
Using the same comparator to measure base to shoulder, cases fired in the Rossi are up to 0.008" longer than those run through the Winchester. I'm going to order a no-go gauge and maybe a field length gauge as well and see what they indicate. I'm also going to cut open a couple cases from the same batch that don't have the ring and see if they show interior signs of stretching.

I don’t think you need the gauges, you have already identified the problem and located the source, even quantified the amount the cases are blow out vs your other rifle.

If you set the die up for your Winchester XPR like this the cases will last longer than if you allow them to blow out and size them more than necessary and repeat until the case splits.

Sounds like it’s even more important on the single shot, so just size the case enough so it closes easily, don’t let the round be loose, likely will get better accuracy too. At least that’s the case with my Contenders.

If you don’t want to destroy cases just to be able to measure wall thickness at different points. You can throw something like this together.

Zero the indicator when the two contact points are touching then slide the case on.

You obviously don’t need to section them, that one is for illustration.

barnfrog · Dec 2, 2021

Steve in Allentown said:
I agree with @243winxb that you shouldn't use the same brass in both rifles.

Understood. Most of the brass I have is once fired. I should have started with new brass to load for a new gun.

barnfrog · Dec 2, 2021

243winxb said:
How much longer then factory new ammo?
Buy new factory ammo for this gun only. Test fire rounds, measure head to datum. Size brass to same. Should stop separations?

Hadn't thought of checking against factory ammo; that's an excellent idea.

I guess an other way to ask one of my questions is, if a chamber is larger than SAAMI spec, could one still safely fire form cases to it and reload them? If so, no need for the gauges, really.

Steve in Allentown · Dec 2, 2021

barnfrog said:
. . . if a chamber is larger than SAAMI spec, could one still safely fire form cases to it and reload them?

I would think the number of modern firearms with chambers that are not within SAAMI specs is awfully small but to answer your question, yes.

If so, no need for the gauges, really.

Correct for bolt action and single shot rifles but you'll still need bump the shoulders back and/or full length resize when extraction gets sticky.

For semi-autos you always have to full length resize and bump the shoulders back otherwise bad things like out of battery detonation can happen.

Kaldor · Dec 2, 2021

Great posts here in regards to this

I would have the gun checked for excessive headspace. That is the reason why your brass is stretching to the point it it almost looks belted. If that doesnt happen, I would only bump the shoulders 2-3 thou and segregate the brass specifically for this rifle. Its not like a single is going to see a high volume of shooting, so you could set aside say 50 pieces for this rifle, and probably have enough brass on hand for a lifetime.

243winxb · Dec 2, 2021

barnfrog said:
Hadn't thought of checking against factory ammo; that's an excellent idea.

I guess an other way to ask one of my questions is, if a chamber is larger than SAAMI spec, could one still safely fire form cases to it and reload them? If so, no need for the gauges, really.

If there is any sign of separation when firing new factory ammo, the Rossi needs repair. Head to datum should be measured before & after firing the factory ammo. The difference may give a clue , if gun has excessive headspace.
If no signs of separation, do minimum sizing just so the action will snap closed .

Head space is controled by the yellow marks. The area can wear, if a used gun.

JFrank · Dec 2, 2021

A standard case gage might be in order.
The only thing expensive about a gage is not having one.

Ranger99 · Dec 2, 2021

243winxb said:
. . . Dont use same brass in both guns.

^ ^ ^ key phrase right there ^ ^ ^

Steve in Allentown · Dec 2, 2021

Here's a link to a good series of videos on reloading. At the 3 minute mark of this video headspace is addressed. The guy is talking about reloading for semi-autos but the concepts are the same for bolt actions and single shots.

As @243wxb points out, being able to accurately measure the distance from the head of the case to the datum line is important. The guy in the video uses a good pair of calipers, Hornady Headspace Gauge Kit, and Hornady Anvil Base Kit. He shows how to use them too.

Here's a link to the Hornady product page.

Walkalong · Dec 2, 2021

Steve in Allentown said:
As @243wxb points out, being able to accurately measure the distance from the head of the case to the datum line is important. The guy in the video uses a good pair of calipers, Hornady Headspace Gauge Kit, and Hornady Anvil Base Kit. He shows how to use them too.

Here is the Sinclair version.

Before and after sizing a once fired 6 Creed case. A meaningless number other than giving you the difference. Of course you
can always zero out the caliper on the unsized case, then it gives you the difference with no math involved, but I like to leave it
and use that number to record where my fired cases where, usually a .001 to .002 spread, depending on brass/chamber/load
uniformity quality. I have never seen 100% of fired cases measure exactly the same at the shoulder.

Bcwitt · Dec 2, 2021

I do the same thing w a 38s case. Put the front of 38s case on shoulder & measure w caliper.

jmorris · Dec 2, 2021

barnfrog said:
I guess an other way to ask one of my questions is, if a chamber is larger than SAAMI spec, could one still safely fire form cases to it and reload them? If so, no need for the gauges, really.

Absolutely that’s what the method I posted in #9 is doing. If the chamber was longer the die would just be backed out that much more, to keep from sizing the brass too much, allowing it to stretch again upon firing again.

On the single shot, you can use the barrel, not sure how the ejector works on the Rossi, spring or mechanical. If it’s mechanical, just close the barrel a bit to lower it, if it’s a spring see if you can depress it while you drop in a case.

Bcwitt · Dec 3, 2021

I once had an 8x57 w a lot of head space (approx .025) I just formed brass from 3006 & located the shoulder to suit the chamber. Never had issues.

Everybody's favorite topic - case head separation

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