More primers backing out

[TimK]

I read through the other thread on this topic and it is very informative. My situation is a bit different.

Load - .308 Win
New Lapua Brass
168g SMK
43.5g Varget
Fed Primer
2.810" COAL

Rifle is a stock Rem 700.

Brass was FL resized on a Lyman die, die set to touch the shell holder. It took a bit of force on the handle, but didn't seem excessive. No other brass prep.

Primers were tight to insert.

No case gage. (one is on order)

I didn't notice while I was shooting, but last night I was decapping the brass and noticed some primers slightly backed out and flattened. No other signs of pressure.

My question is this: If I'm planning to just neck size from now on, do you think I did enough damage to the cases to worry about them? Are they safe to shoot again? How can I inspect a decapped case to determine if it's good?

Follow up question: Will my soon-to-be-delivered case gage be useful to me if I'm just neck sizing?

 

[oneshot onekill]

Re: More primers backing out

I can tell you I wasn't able to fit "fired" cases into the case-gauge I borrowed but I don't know where they bind. Seems it's near the back of the shell. I think once they're fire-formed to your chamber you can't use the case-gauge anymore.

I'd full-length size them again and check them with the gauge the first time. Then neck-size after you're sure they're right.

 

[mjb2]

Re: More primers backing out

Reads as if you may be oversizing the cases. If the shoulder is pushed back too far, primers may backout slightly upon firing as the case is pushed forward to meet the front of the chamber. If case pressure is low enough, it may nor expand and fully "reseat" the primer. Are there any other signs of high pressure such as primer cratering (which may because of an oversized firing pin channel) or ejector marks or swipes on the fired case head ?

Case guage will work for resized cases / loaded rounds. But as noted, it is set for one "spec" that your particular chamber may not meet. Neck sized cases are really only good for your particular rifle because of this fact. And that's why they may generally be more accurate than fully resized cases.

You haven't hurt the cases enuf to worry about.

 

[Grump]

Re: More primers backing out

I'm lucky in that both chambers I'm loading for produce fired cases that will go into the Wilson gage.

Makes it easy to compare fired with sized and make sure anything is changing.

One method is to start backing out your sizer die 1/12 of a turn at a time (half the hex--flat to point, point to flat, etc.) using a nice Sharpie-marked index on the die body, until the resized cases chamber stiff or just won't let the bolt fully close. Go back in 1/12 a turn, lock the die down, and be consistent with your case lube from now on.

A skimpy-lubed case *can* compress slop in the system and perhaps add some flex, and get resized a tiny bit less than a properly-lubed case. Sorry, but I forgot whatever numbers I got, if I even measured them. Think thickness of 24-lb paper, max.

A LOT of cases have been ruined after only 3 reloadings by doing the default "turn the die down to contact, plus 1/4-turn" instructions. Mine. That other barrel's chamber was done by the 'smith, intentionally, a bit long as a compromise for USGI ammo. It's supposed to make true slam-fires less likely (they were strongly correlated with shorter chambers).