primer problems

[redeye]

Been reloading for approx. 20 years, mostly hunting loads though. Recently had a custom 7mm wsm target rifle made and it's been a whole new experience. Went to a competion shoot today with the same loads I shot back in April. The temp was up about 15 degrees (90 degrees today) and the humidity up about 50% today. Peirced holes in 15 of 18 rounds, messed up my trigger of course but other than the hole in the primer had no other signs of extreme pressure. Never had this happen before, I've blowed primer pockets and other stuff but never this. Can this be a result of my firing pin being to long after having my bolt resurfaced or just simply to much pressure? Thanks for any feedback,
Redeyegun)

 

[RDM416]

It could be either one. I suggest loading a few with a mild load and see if you are still having primer problems. Obviously, it would be the firing pin for sure.

Rounds that are loaded close to edge of being over pressure can really act up on a hot day as well. If I am shooting on a hot day I either keep my ammo in the truck with the A/C on max or in a small cooler sitting on top of some ice. Put some of your current loads on ice, then shoot a few and see what happens.

 

[rscott5028]

I have a Steyr SL in 223 that's fired a lot of rounds without issue. I usually just shoot the cheap stuff and don't even handload for it.

Last time out, I tried a box of Superformance and it pierced holes in several primers. I think it was only ~80F that day.

I just haven't had a chance to debug that.

I suppose I'll disassmble/clean the bolt. Then, mic and inspect the firing pin before I go shoot again. Length and shape both make a difference. ...although, I can't see how shape would change over time and if the bolt was dirty or gummed, I would expect it to protrude less on firing.

Unless I find something unusual, I'll probably just go back to the stuff that works. Perhaps it was a bad lot of primers from Hornady?

-- richard

 

[redeye]

Thanks for the reply guys, It's strange I never heard of anyone putting their ammo on ice but I did think about that the other day at the shoot. I think I might try that.
REDEYE

 

[RDM416]

redeye, I don't know how common it is to put ammo on ice but it works for me on those hot 100+ degree days. It's also not like cooling down beer or cokes.: I just take a small cooler with about 4 inches of ice in the bottom. My plastic ammo boxes just sit on top of the ice not down in it.

I have done quite a bit of temperature testing and it is quite surprising (or at least it was to me) how much temperature effects your ammo. Some powders are more stable than others but I can tell you for sure if you do your load development on a nice 65 or 70 degree spring day, then go shoot those same rounds after they sat around on your bench for an hour in 100 degree heat........ they will be "hotter". (pun intended)

 

[rscott5028]

Just be careful to dry the ammo before chambering.

I haven't experienced it. But, I've read that water in the chamber (including condensation from icing down your shells) will cause dramatically increased pressure.

I haven't verified that. But, I thought I'd pass it along.

-- richard

 

[Mikecr]

It causes increased BOLT pressure, because the round slams backward against it.
Allowing brass to drop below dewpoint is a bad idea.
And same with a barrel..

Better to heat loaded ammo during load development, and field use.
I keep loaded rounds in a pant pocket, and hot or cold outside, the ammo stays near a very well regulated body temp.
There will still be changes to bore dimensions from 15 to 90degs. But a competitor would have prepared for this, I'm sure..