Degrees of separation

[Highpower-FClass]

Found a good additional use for the Teslong.

Shooting service rifle works the brass hard even if being careful when resizing. Case head separations do happen. My daughter's rifle is especially hard on the brass for whatever reason.

Below are some pictures of different stages of separation, taken with the teslong. I am adding this as step to my brass prep, tedious but beats having a case separate during rapids.

In this case, a shadow can be seen when rotating the case but very faint in a single picture



In this case the incipient separation is further along and easier to see


Even more separation but no visible indication on the outside of the case. Would not want to shoot this in a match.


This one is full-on separating with a visible ring on the outside of the case. Scratches are from paperclip, which catches well in the ridge.

 

[Bill K]

Just a thought on your daughter's rifle being hard on brass. Are you setting the should back too much when reloading her's ? Have some slight resistance in chambering and see if that doe's not slow the case separation down, if that is what it is doing and you mean.

 

[jepp2]

Below are some pictures of different stages of separation, taken with the teslong. I am adding this as step to my brass prep, tedious but beats having a case separate during rapids.

Great summary showing the progression. The only time I have seen my cases develop that much stretch was a 223AI I purchased used, and I knew it had excessive headspace.

 

[milboltnut]

how many firings do you get before the pic above happens? Are you partial FL sizing?

 

[Ringostar]

Some bench rest shooters don’t understand service rifle. The cases need to be sized down, to reliably mag feed in a semi auto during rapid fire strings. I tried it 15 years ago. However I’m too old, fat and non flexibl, to get into the sitting position.

 

[K22]

I haven't fired a semi-auto since my days in the Army almost 50 years ago so my post may not be applicable but I'll offer some suggestions based on my experience with bolt rifles. The important point here is that this condition must not be ignored and corrective action must be taken.

First I have the head space checked by a rifle smith. If this checks out to be within specs then I'd evaluate my sizing procedure.

I'd measure some fired cases (primer removed) with a bump gauge. The conventional "wisdom" is to bump the shoulder back about .003" for semi-auto's but this may be too much for your rifle.

I'd set my FL size to just firmly touch the shoulder (i.e. no shoulder set back), size then measure the case with the bump gauge. The measurement should be very close to the fired case measurement. I then would check that case chambering in the rifle. If it chambers without issue then I'd size a few more and check them. If they all chamber without issue then I'd use that as my set point for the die. If not, I'd turn the die down a slight amount and repeat the process until the case chambers without issue. Record that measurement as your new base line shoulder set back point.

Which ever course of action you decide, you should investigate this issue with a rifle smith - case head separation must be avoided at all costs. Any suspect cases should be discarded even one's which have the shoulder set back too far if revealed by the aforementioned measurements.

 

[johara1]

Is the reamer a little oversized ? do you see any expansion ahead of the web? and if you size the brass too much this is what you get. Mic a fired case and sized one and compare the difference...... jim

 

[Highpower-FClass]

Some bench rest shooters don’t understand service rifle. The cases need to be sized down, to reliably mag feed in a semi auto during rapid fire strings. I tried it 15 years ago. However I’m too old, fat and non flexibl, to get into the sitting position.

Yeah, reliable feeding is a must, otherwise the rapids are toast. AR-15 extraction is a very violent event compared to bolt action rifles. It subjects the cases to a lot of stress, no way around it.

I haven't fired a semi-auto since my days in the Army almost 50 years ago so my post may not be applicable but I'll offer some suggestions based on my experience with bolt rifles. The important point here is that this condition must not be ignored and corrective action must be taken.

First I have the head space checked by a rifle smith. If this checks out to be within specs then I'd evaluate my sizing procedure.

I'd measure some fired cases (primer removed) with a bump gauge. The conventional "wisdom" is to bump the shoulder back about .003" for semi-auto's but this may be too much for your rifle.

I'd set my FL size to just firmly touch the shoulder (i.e. no shoulder set back), size then measure the case with the bump gauge. The measurement should be very close to the fired case measurement. I then would check that case chambering in the rifle. If it chambers without issue then I'd size a few more and check them. If they all chamber without issue then I'd use that as my set point for the die. If not, I'd turn the die down a slight amount and repeat the process until the case chambers without issue. Record that measurement as your new base line shoulder set back point.

Which ever course of action you decide, you should investigate this issue with a rifle smith - case head separation must be avoided at all costs. Any suspect cases should be discarded even one's which have the shoulder set back too far if revealed by the aforementioned measurements.

I think you are correct that I might need to try sizing a bit less for this particular rifle. The headspace of the chamber is the same as on my rifle and I currently FL size 2-3 thousands. That works fine for my rifle but it does seem to be working the brass too much in my daughter's rifle. I also suspect the chamber is a smidge tighter, holding the brass more tightly during the extraction. It does not seem to be over gassed and I switched to a heavier buffer which seems to have helped a bit.

It's a balancing act as failure to fully chamber is a much more disruptive event in service rifle as compared to F-class, especially during rapids. With bolt rifles you can just force the bolt down with a fair amount of leverage. The forward assist on an AR is close to useless.

Is the reamer a little oversized ? do you see any expansion ahead of the web? and if you size the brass too much this is what you get. Mic a fired case and sized one and compare the difference...... jim

I have mic'ed the cases and they seem fine. My current theory is that this particular chamber ends up binding the brass harder on firing, subjecting the case to more stress during extraction.

how many firings do you get before the pic above happens? Are you partial FL sizing?

The worst one is 6 firings. But it also seems like individual pieces of brass are just more susceptible to it. I have seen pretty severe separation on occasional cases after 3 firings, while a vast majority in the same batch show no indication.

 

[D-4297]

Here's a thought to mull over . Why not use a small-base die to size the bodies of the cases you load for baby girls rifle . Then ; run the thru the regular sizing die , to set the bump back on the shoulder , and do the neck . Sounds like the brass is expanding diametrically when fired , causing hard extraction . You may even want to check diameter of fired brass , before processing it . That chamber might be just plain wore out , even though the barrel isn't .

 

[Mad_Charlie]

I have been using my borescope(s) to look inside my cases ever since I got one three years ago. I have seen some "interesting things".