Lapua Palma Brass and flash hole dia?

[Heavies]

I have been using the Lapua Palma small primer .308 brass for a while now. I like this brass, however, I have been running into an issue.

I live in a warm climate and the temp never drops below the 80's when I shoot, but I have still been having misfires using this brass. When I pull the bullets the powder looks discolored and I can smell the primer has fired, however the powder itself did not ignite.

I decided to take a few cases and ream out the flash hole to .060" to see if that would have any effects. I chronoed 5 cases with the small flash hole diameter, then with the same load and cases, I enlarged the flash hole, and that dropped the ES and SD by a pretty good margin. But keep in mind that I only tested these 5 cases thus far.

I thought this might be interesting to discuss seeing that in smaller cases like 6BR, enlarging the flash hole is not recommended.

I am thinking that the volume of the .308 is too much for the small primer to efficiently ignite, and thus enlarging gave me better ES/SD numbers, and hopefully eliminate misfires. While still keeping the advantage of the small primers less effect on the whole system, keeping the increased strength of the thicker case base, and keep vertical dispersion to a minimum.

Has anyone done this with their Lapua Palma cases, and have you had any ill effects from doing this?

 

[mr45man]

Could be just your particular combination of powder and primers?
John H.

 

[FroggyOne2]

Uniform your primer pockets, make sure you ream the flash holes and use a magnum primer and see if that don't help some.

 

[spclark]

I inside-chamfer (de-burr) each flash hole on this brass, ever since I started using it the year it appeared. I use a K&M small hole tool, I think it's 0.062".

Only FtF's I've experienced in over 3,000 rounds loaded & fired I traced back to cases that must have been still wet (denatured alcohol) when primed / charged as the powder was lumped together at the bottom. The primers had fired but the powder likely was still damp.

Powder's been 90% IMR8208XBR since it came out, N-150 before that. The only primers I've used were CCI BR-4's at first then I switched to Wolf / Tulammo KVB-223REM, a standard primer in a magnum-primer cup. Where I shoot it can be 45 F up to 100, maybe more. Outside that range I usually don't get my gear out.

Initial load testing indicated SD's < 10 & velocity @ 2975 fps with Berger's 155 Hybrid in one rifle, 3125 fps w/ Sierra's 2156 155 in an older one.

I have noticed some few burrs on the flash holes when new and the K&M tool will not enter the flash hole unless it's being turned so the holes must be 0.060" from the factory, just not too uniform.

I'd look first to see if your FP indents are centered nicely, then at your primer / powder seiection.

Too, your primers need to be seated firmly & this varies some depending on what primer and priming tool you use. I prefer Sinclair's.

 

[Darrel Martin]

I had some hangfires until I went to Rem 7 1/2 bench rest primers.No problems since then,shooting Varget and 155vlds.I don't recall my ES but it was not bad.

 

[Heavies]

Thank you for the replies. I have done all that has been suggested. I am using 168 hybrids, 8208 powder, and CCI450 mag primers.

I had misspoke in my OP, the hole was reamed to .080" My SD of 10 dropped to 2 in a five shot string, with the same pieces of brass. Ten rounds is not statistically significant, however I didn't expect the numbers to be that good. Accuracy was the same, velocity slightly dropped with the larger hole.

With the SD improvement and the velocity decrease, I was thinking that this may mean the powder was being ignited more efficiently.

 

[Heavies]

No other thoughts?

I've read that Danny Biggs, IIRC, used small primer Remington brass with the large flash hole for his match winning loads.