Lapua .308 "Palma" brass

[Will Munny]

I'm having a cratering problem with Lapua Palma brass, I have normally shot "regular" .308 Lapua brass but figured Id try the new "palma" (small rifle primer brass) and its cratering the primers, I'm using the same load of 44gr of Varget, 175gr Sierra match king CCI BR large and small rifle primers same OAL same rifle.

The "large rifle" Lapau primers look fine no problems at all (like they've always been) but the small rifle primer (palma) are cratering almost to the point of piercing the primer

Is anyone else having this problem? Can anyone explain this to me??

I'm shooting a Rem 700 .308 with blueprinted trued action & bolt.

Thanks in advance

 

[Robert]

I'm having a cratering problem with Lapua Palma brass, I have normally shot "regular" .308 Lapua brass but figured Id try the new "palma" (small rifle primer brass) and its cratering the primers, I'm using the same load of 44gr of Varget, 175gr Sierra match king CCI BR large and small rifle primers same OAL same rifle.

The "large rifle" Lapau primers look fine no problems at all (like they've always been) but the small rifle primer (palma) are cratering almost to the point of piercing the primer

Is anyone else having this problem? Can anyone explain this to me??

I'm shooting a Rem 700 .308 with blueprinted trued action & bolt.

Thanks in advance

Will,
What is your firing pin dimension?

SR primers work better with .063 (1,6mm) firing pin tips and accordingly reduced protrusions. Also, the FP hole in the bolt head must correspond to the FP tio diameter.

Larger dameters firing pins and corresponding protrusions allow craaterisation with SR primers, as the ignition starts before the FP tip covers entirely the surrounding hole diameter, allowoing primar cup metal to flow around the tip.
R.G.C

 

[BoydAllen]

When is the last time that you changed your firing pin spring? Also, my factory actions, on small rifle primered calibers, generally crater, but they don't pierce. Someone, who should know, once told me that a properly shaped Remington firing pin tip should have two radii, a larger one surrounding the center, and a smaller one at the transition to the side. If your pin tip looks too much like a hemisphere, that can contribute to cratering., as can a lighter than stock firing pin, without a heavier spring.

 

[memilanuk]

Send the bolt off to Gre-Tan Rifles to have the firing pin hole bushed and the firing pin turned to fit. $82 (includes return shipping) and you'll have it back in about a week. With the slop around the firing pin hole in most factory bolts (regular action truing doesn't touch this area) and the high pressure loads we tend to run, cratering is common especially with the small primer cases. While its true that it often won't actually pierce, when temperatures get warmer they can. Bushing the firing pin hole eliminates the problem.

 

[watercam]

Or, if there is no other issue, keep shooting. I am using Fed. 205Ms in a Win. 70 with Speed-Loc firing pin and they crater slightly but they go bang, are accurate and reload perfectly. Perhaps the pin protrudes a tad to far?

 

[Rust]

Go to a primer with a harder cup. All small rifle primers are not the same hardness/thickness. It's been written up a couple of times somewhere, just don't recall where on one of the high power sites.