Excessive headspace from shoulder bump.

03machstock · Sep 3, 2024

.308 winchester
Remington 700, shilen barrel
Don’t know chamber specs
Lapua brass

I was shooting with a buddy and every 25th round or so the case head would separate on the brass (3 total). I took a couple of pieces and measured them with a headspace comparator and of course I forgot to write the numbers down but he was bumping the shoulders back .015” on his reloads compared to the fired case. I told him that’s more than likely the cause and offered to help him set up his dies properly. The problem, he has a few hundred rounds loaded up like this and it’s lapua brass. Is there any safe way to go about blowing them back out? Ie shooting them out of an ar 10 and then annealing them or pulling all the components and sending them out to be hydro formed? What about the other pieces that have been shot but haven’t split yet, are those still safe to use pending the dies set up correctly? I didn’t have an answer for him so I’m posting here.

HMRamateur · Sep 3, 2024

Not saying this is the way, but just a thought. Maybe reducing powder charges to form the brass, or low powder charges with just a wad?

I'm sure the fired pieces that haven't split are safe, but could have reduced life as a a result. Not an expert though so take my comment for what it's worth.

BenE · Sep 3, 2024

03machstock said:
.308 winchester
Remington 700, shilen barrel
Don’t know chamber specs
Lapua brass

I was shooting with a buddy and every 25th round or so the case head would separate on the brass (3 total). I took a couple of pieces and measured them with a headspace comparator and of course I forgot to write the numbers down but he was bumping the shoulders back .015” on his reloads compared to the fired case. I told him that’s more than likely the cause and offered to help him set up his dies properly. The problem, he has a few hundred rounds loaded up like this and it’s lapua brass. Is there any safe way to go about blowing them back out? Ie shooting them out of an ar 10 and then annealing them or pulling all the components and sending them out to be hydro formed? What about the other pieces that have been shot but haven’t split yet, are those still safe to use pending the dies set up correctly? I didn’t have an answer for him so I’m posting here.

How many loads are on the brass? I would likely pull it down and scrap the brass depending on the answer

Im2bent · Sep 3, 2024

@spife7980 ? Pull the bullets and fire form?

supercorndogs · Sep 3, 2024

How many times has the brass been fired? If it's sevral its proabaly ruined. Growing .015 once shouldn't separate it. (I would gues 3 or 4x with that bump.) You can blow shoulders on brass forward by jamming bullets into the lands or expanding necks a caliber size up then sizing the next back down slowly until you get a slight crush fit in the chamber with the oversized portion of neck.

spife7980 · Sep 3, 2024

Im2bent said:
@spife7980 ? Pull the bullets and fire form?

I don’t know, I’d probably just shoot it and try to do better the next cycle.

supercorndogs · Sep 3, 2024

Buy ruined I don't mean throw it all away. But I would be checking it all for thinning at the web and culling stuff getting ready to separate.

BuildingConceptsllc · Sep 3, 2024

Shooting it in a bolt gun would be a lot better if he has that option. Otherwise he's going to have to just shoot it and try to do .003" bump next time.

03machstock · Sep 4, 2024

He just got back to me, said it’s been reloaded 4 times.

WasNH4X · Sep 4, 2024

After pondering this predicament a few minutes.... I'd pull one bullet, load a min. powder charge...seat bullet where it is in the lands....fire and do me some measuring......then ponder some more

supercorndogs · Sep 4, 2024

I woukd shoot them all inspect the brass trash the ones I can see thinning and getting ready to separate, then re-adjust my set up so as to not bump shoulder so much. Might need all new brass. Might be some good ones still.

Doom · Sep 4, 2024

I don't think reducing the charge is going to buy much. The case is still going to grow about the same amount. Unfortunately this brass is going to have a short life.

BuildingConceptsllc · Sep 4, 2024

Doom said:
I don't think reducing the charge is going to buy much. The case is still going to grow about the same amount. Unfortunately this brass is going to have a short life.

Yeah, if it's been sized that much 4 times and shot out, she's taken a lot of abuse. No way to make it last a long time at this point.

Edsel · Sep 4, 2024

03machstock said:
He just got back to me, said it’s been reloaded 4 times.

The brass must have really been compressed excessively for it to fail on the 4th firing.

For .308 Winchester loads using nice brass, one can typically get up to 20 - 30 firings when accurately matched to the chamber, even with “hot” loads.

WasNH4X · Sep 4, 2024

Edsel said:
The brass must have really been compressed excessively for it to fail on the 4th firing.

For .308 Winchester loads using nice brass, one can typically get up to 20 - 30 firings when accurately matched to the chamber, even with “hot” loads.

OP stated .015 shoulder setback.

After eating breakfast and pondering some more........I'd pull components ,and scrap the brass. Three case head separations have already happened.....which can't be doing any to the good for the chamber.......chalk it up to one of them " Don't do dat again " lessons....ie. " Raise ram ,screw die down to touch shell holder ,lower ram , screw die down a tad more , size brass."

Im2bent · Sep 4, 2024

Say one wanted to load for a rifle without knowing headspace dimensions. In other words make your own "factory" ammo. Commercial ammo is made to fire in every chamber so are they sizing to min saami?

Edsel · Sep 4, 2024

Im2bent said:
Say one wanted to load for a rifle without knowing headspace dimensions. In other words make your own "factory" ammo. Commercial ammo is made to fire in every chamber so are they sizing to min saami?

Pretty much.

03machstock · Sep 4, 2024

Thanks for all the reply’s guys, I’ll forward the messages along and help get him set up going forward.

Edsel · Sep 4, 2024

Handloading Anecdote:

Sometimes, the bolt closes with resistance on brass which does in fact have appropriate headspace documented by a comparator, say -0.001” to -0.002”.

Because of failure in bolt closure - one ignores the comparator measurement, and twists the die tighter - getting the bolt to close - but consequently, the shoulders have been bumped by -0.015”.

What happened was that the die was forced a bit lower on brass with a bloated body. The bolt closed with less resistance due to the body being sized more appropriately (from the die now being a tighter or lower position), however at the expense of the shoulders (also from the die now being a tighter or lower position).

This is an idiosyncracy from variations in chamber sizes that one must keep in mind.

Doom · Sep 4, 2024

Edsel said:
Handloading Anecdote:

Sometimes, the bolt closes with resistance on brass which does in fact have appropriate headspace documented by a comparator, say -0.001” to -0.002”.

Because of failure in bolt closure - one ignores the comparator measurement, and twists the die lower - getting the bolt to close - but shoulders have been bumped by -0.015”.

What happened was that the die was forced a bit lower on brass with a bloated body. The bolt closed with less resistance due to the nody being sized more appropriately, however at the expense of the shoulders.

This is an idiosyncracy from variations in chamber sizes that one must keep in mind.

@Edsel, If I may add.

Without getting into a deeper discussion of the specifics of this case, one of the most frequent causes of excessive shoulder setback occurs when cases from one rifle are resized for use in a different rifle. This can occur when the base of the cartridge has expanded to a dimension that exceeds the chamber diameter at the base and the die is lowered further than recommended to try and size the base (at the 0.200" SAAMI dimension). This is one of the reasons that it is recommended to use only cases from your rifle for reloading.

I find it unusual that any die would end up setting the shoulder back 15/1000th on multiple sizings. It leads to ash two questions for the OP:

1) How was the die set up?
2) Has the headspace on this chamber been checked? (both Go and No-Go)

Edsel · Sep 4, 2024

Doom said:
This is one of the reasons that it is recommended to use only cases from your rifle for reloading.

FULL LENGTH SIZING AND BRASS HYSTERESIS

www.snipershide.com

Yes.

One chamber, one batch of brass, one die = One sizing setting

Going beyond bubbasayso and bubbalore, we managed to pull up a reference which discussed the properties leading to such (in part, at least) in the thread linked above.

03machstock · Sep 4, 2024

Doom said:
@Edsel, If I may add.

Without getting into a deeper discussion of the specifics of this case, one of the most frequent causes of excessive shoulder setback occurs when cases from one rifle are resized for use in a different rifle. This can occur when the base of the cartridge has expanded to a dimension that exceeds the chamber diameter at the base and the die is lowered further than recommended to try and size the base (at the 0.200" SAAMI dimension). This is one of the reasons that it is recommended to use only cases from your rifle for reloading.

I find it unusual that any die would end up setting the shoulder back 15/1000th on multiple sizings. It leads to ash two questions for the OP:

1) How was the die set up?
2) Has the headspace on this chamber been checked? (both Go and No-Go)

1. It’s a full length sizing die and when I asked about shoulder setback he had no clue what I was talking about, so I’m assuming he just screwed it down and ran cases through it.
2. The impression I got, the build is probably 15 years old now, but it was a cut by a pretty good smith, so I would assume headspace is good to go on the rifle side of things. But it won’t hurt to check.

Edsel · Sep 4, 2024

03machstock said:
2. The impression I got, the build is probably 15 years old now, but it was a cut by a pretty good smith, so I would assume headspace is good to go on the rifle side of things. But it won’t hurt to check.

A smith, in the end, is just an artisan prone to errors like the rest of us.

I learned the hard way not to rely on “assumptions of grand eminence” after realizing that the 1/12” Lothar Walther barrel that came with my very first Accuracy International AT was horribly out of spec.

Probably my most bloated chamber, even worse than my ARs. Still have it, kept as a souvenir.

That rifle was my first foray into handloading and laid down the the foundations to build on subsequently.

Unfortunately, I only started looking more closely after 3,000 junker rounds or so, and only came to the realization after having bought new barrels.

I simply didn’t know any better early on.

Doom · Sep 4, 2024

03machstock said:
1. It’s a full length sizing die and when I asked about shoulder setback he had no clue what I was talking about, so I’m assuming he just screwed it down and ran cases through it.

Unfortunately some dies give instructions but don't even mention headspace which I personally don't agree with but no die should set the headspace back that far if the chamber is correct and the die is properly set. It would take the die being at is shortest dimension and the chamber being at its maximum to get 0.013" setback. I would also consider that he may be shooting some hot rounds leading to base expansion issues and trying to size that part of the case back down. Sounds like some training is in order. Good luck!

PB&J. · Sep 4, 2024

Im2bent said:
Say one wanted to load for a rifle without knowing headspace dimensions. In other words make your own "factory" ammo. Commercial ammo is made to fire in every chamber so are they sizing to min saami?

And the "factory" only intends on their brass holding up for one firing. They don't care about reloaders or having reuseable brass afterwards.

Edsel · Sep 4, 2024

Always run away from brass of questionable pedigree, unless you want to practice shining turds.

supercorndogs · Sep 4, 2024

Doom said:
Unfortunately some dies give instructions but don't even mention headspace which I personally don't agree with but no die should set the headspace back that far if the chamber is correct and the die is properly set. It would take the die being at is shortest dimension and the chamber being at its maximum to get 0.013" setback. I would also consider that he may be shooting some hot rounds leading to base expansion issues and trying to size that part of the case back down. Sounds like some training is in order. Good luck!

I have a Lyman 223 die that I am pretty sure set the shoulder back enough to cause chs on some 2x fired. I will dig it out and check when I get home. Maybe I was mistaken but I think it was setting shoulders back like twice that sizing to the shell holder.

supercorndogs · Sep 4, 2024

PB&J. said:
And the "factory" only intends on their brass holding up for one firing. They don't care about reloaders or having reuseable brass afterwards.

Factory ammo is the same size as new brass. You get lots of life if you don't keep stretching and compressing it.

PB&J. · Sep 5, 2024

supercorndogs said:
Factory ammo is the same size as new brass. You get lots of life if you don't keep stretching and compressing it.

Factory ammo and new brass are sized toward the minimum end of SAAMI cartridge spec, and factory rifles are chambered toward the maximum end of SAAMI chamber spec. What you get is small brass in a large chamber from the very first firing, which has exactly the same effect as excessively resized brass. This first firing is unavoidable.
How far it has been stretched and how many subsequent firings it will last depends on how far on either end of the extreme the brass and chamber are, and how much it is sized back down be the reloader. The manufacturer doesn't care about subsequent firings as it's not their problem, as long as the brass survives the first firing their job is done. If you keep resizing brass to "factory" dimensions it will not last long at all...
A perfect example of this is 300 win mag. That brass will generally stretch 0.012-0.015 on the very first firing. In fact, peterson specifically makes a "long" win mag brass to reduce the stretch of new brass on the first firing.

You can think of it like hearing damage, the first loud noise will generally not end in complete deafness, but that doesn't mean the damage is not there, and every subsequent exposure is cumulative.

supercorndogs · Sep 5, 2024

Not all brass is closer to min Sammi spec and not all factory chambers are closer to max. There are ways to avoid the initial stretch buts its not really nessasary to achieve good brass life. Not oversizing on subsequent firings is more important.

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