308 palma brass flash hole

[scott/r]

Just wondering if you guys know of any benefits in enlarging the small flash hole in the palma brass? I think I've heard talk or read somewhere that it's supposed to speed things up a bit, or is that just something I've just got in my head?
I was under the impression that the small flash hole was a big help in keeping sd/es figures down. Is that right?
Any idea what size the large flash hole is to be drilled out to? If it's a viable thing of course.
Scott.

[Rich4]

I believe in a foggy memory enlarging the flashole negated the benefits of the small primer by reducing pressure in the flash and increasing combustion pressure in the pocket, I believe the test results were in the book A Benchrest Primer, I’ll check when I get home, Paul Matthews actually used a swaging tool to reduce the flashole for long range black powder use

[BATattack]

I've tested both lapua and alpha brass side by side. Alpha brass has a SRP but comes standard with a large flash hole. Both with standard and 450 primers

I couldn't see any discernable difference in ES, velocity or pressure handling capability between the two different flash holes OR primer types which was a surprise to me. I was expecting to see the same as you mention above.

[Brad Y]

I did find some benefit by enlarging it but in warm conditions I think you will get better performance and more consistent ignition. Drop that down below 10 degrees and it starts getting a bit more hit and miss. If I was choosing a 308 and 155gr combo I would use 8208 and srp brass all year round.

[scott/r]

Thanks guys for responses. Much appreciated.
Scott.

[Rich4]

Found one of the tests, Angerman in 1983 used high speed cameras and discs with .082” .070” .060” .052” and .040” he saw a linear reduction in flash volume all the way down, the focus of the test was checking consistency by weighing before and after firing to determine the amount of compound per primer

[mitchellchandler_au]

I did a test a little while ago with 10 pieces of 308win palma brass. I fired a 10 shot group with the flash holes untouched, then opened them up to standard size. I found no real difference in group size or es/sd. I was using my accuracy international rifle as the test bed. For something different i grabbed 10 large rifle primer lapua cases, using the same load as the palma cases i did the same test. I found the velocity was about 30fps higher in the large primer cases and the es/sd opened up a bit, still single digits just a touch higher. I found the small flash hole k and m uniformer takes the flash hole to about half way between small and large, the decapping pin in my wilson die slides through with minimal room now

[Tim L]

Found one of the tests, Angerman in 1983 used high speed cameras and discs with .082” .070” .060” .052” and .040” he saw a linear reduction in flash volume all the way down, the focus of the test was checking consistency by weighing before and after firing to determine the amount of compound per primer

I can't help but wonder what they thought was being wieghed given the tiny amount of compound compared to inconsistencies in the mechanical components, plus the wax (which is just sprayed on).

There is a whole lot of crap that comes out of a primer that has nothing to do with ignition.

Have you got a link to the test? I'll try and redo it. Results are meaningless if they can't be repeated.

[Rich4]

No links, this is old school from books, I could scan the pages and email them to you, MAYBE depending on cantankerous email accounts

[Tim L]

No links, this is old school from books, I could scan the pages and email them to you, MAYBE depending on cantankerous email accounts

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