308 palma brass flash hole

Get or give advice on equipment, reloading and other technical issues.

Moderator: Mod

Message
Author
scott/r
Posts: 885
Joined: Wed Aug 27, 2014 8:22 pm
Location: far north brisbane

308 palma brass flash hole

#1 Postby scott/r » Sun Dec 06, 2020 8:55 am

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
Posts: 534
Joined: Sun Feb 24, 2019 2:33 pm
Location: Chinchilla

Re: 308 palma brass flash hole

#2 Postby Rich4 » Sun Dec 06, 2020 9:28 am

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
Posts: 1275
Joined: Mon Dec 29, 2008 10:29 pm

Re: 308 palma brass flash hole

#3 Postby BATattack » Sun Dec 06, 2020 9:33 am

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
Posts: 2181
Joined: Fri Jun 26, 2009 8:21 pm

Re: 308 palma brass flash hole

#4 Postby Brad Y » Sun Dec 06, 2020 3:46 pm

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
Posts: 885
Joined: Wed Aug 27, 2014 8:22 pm
Location: far north brisbane

Re: 308 palma brass flash hole

#5 Postby scott/r » Thu Dec 10, 2020 4:24 am

Thanks guys for responses. Much appreciated.
Scott.

Rich4
Posts: 534
Joined: Sun Feb 24, 2019 2:33 pm
Location: Chinchilla

Re: 308 palma brass flash hole

#6 Postby Rich4 » Thu Dec 10, 2020 6:02 am

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
Posts: 163
Joined: Sun Apr 02, 2006 8:29 pm
Location: MIA

Re: 308 palma brass flash hole

#7 Postby mitchellchandler_au » Thu Dec 17, 2020 11:10 am

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
Firepower usally means an increased number of misses per minute. 50 misses are not firepower. One hit is firepower

Tim L
Posts: 876
Joined: Mon May 19, 2014 7:11 pm
Location: Townsville

Re: 308 palma brass flash hole

#8 Postby Tim L » Thu Dec 17, 2020 11:35 am

Rich4 wrote: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
Posts: 534
Joined: Sun Feb 24, 2019 2:33 pm
Location: Chinchilla

Re: 308 palma brass flash hole

#9 Postby Rich4 » Thu Dec 17, 2020 5:12 pm

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

Tim L
Posts: 876
Joined: Mon May 19, 2014 7:11 pm
Location: Townsville

Re: 308 palma brass flash hole

#10 Postby Tim L » Thu Dec 17, 2020 5:31 pm

Rich4 wrote:No links, this is old school from books, I could scan the pages and email them to you, MAYBE depending on cantankerous email accounts #-o

PM sent
Sent again, my sent box was full :?


Return to “Equipment & Technical”

Who is online

Users browsing this forum: G.T and 47 guests