Primers pressure signs

[thealexstop]

Worked up to 37gr lil gun, OAL 2.300, 300 gr SST, starline brass, 450 primers in a CA ridgeline and a can. Getting some imprints in the primers. No stick in bolt lift. What are your thoughts? Think pressure is around 50k? I’m getting speeds of 2240 FPS groups 1”….. working on photos of the primers. It says the file is too big. Stay tuned.

[Al in Mi]

This is my take.

looks like a bit of cratering around the firing pin, edges of the primer don't show any filling out from the classic pressure signs I've seen.

I' have a bit of cratering like that with my 700 when brass is at the low end of length, that guns chamber is right at the high end for length thou.

I'm personally not a fan of Lilgun with heavy bullets for top speed. H110/296, 1680, or CFE BLK have been the work horses in that dept for me.

[thealexstop]

Im wondering if the firing pin hole is a little big on my new gun. why do you not like lil gun for heavy bullets?

[Al in Mi]

I sorta live on the edge of speed if the accuracy is there. Lilgun has always gave me across the board accuracy, but would run into pressure way quicker then I would with H110/296, 1680, or CFE BLK especially with bullets over 250gr.

[coyote wacker]

Would say your brass is a little too short or chamber is a little long....

I have a 50 B&M Super Short have a lot of some brass that has been shot 20 times and counting and also know several people with them....all loads pushing 60'000 psi....it is basically like the 450 BM straight case no shoulder 1.65" long rebated rim...I've never had a problem like the 450 BM were brass gets shorter is it is fired....I think the problem is lower pressure in the 450 BM allowing the neck to get pushed forward on firing....it also could be Winchester 70 CRF on the 50 B&M SS not allowing brass to move when firing....
Have one lot 450 BM brass that have been fired 4 times at close to 60'000 psi in a bolt action only and it is still OK not getting shorter nor need to be trimmed....

[Hoot]

Would say your brass is a little too short or chamber is a little long....

I have a 50 B&M Super Short have a lot of some brass that has been shot 20 times and counting and also know several people with them....all loads pushing 60'000 psi....it is basically like the 450 BM straight case no shoulder 1.65" long rebated rim...I've never had a problem like the 450 BM were brass gets shorter is it is fired....I think the problem is lower pressure in the 450 BM allowing the neck to get pushed forward on firing....it also could be Winchester 70 CRF on the 50 B&M SS not allowing brass to move when firing....
Have one lot 450 BM brass that have been fired 4 times at close to 60'000 psi in a bolt action only and it is still OK not getting shorter nor need to be trimmed....

You're right in that the 450b needs more pressure than SAAMI spec to lock the case in place inside the chamber. The lower pressure as you surmised, allows the case to shorten a little with each successive firing. Holding my loads to 38k PSI or less renders them too short after as little as four loadings. At least that's been my experience with my AR platform. Starline brass, being a little harder than Hornady, resists shortening a few more loadings. In bolt rifles, where higher pressures are less of a risk, the case should lock in pretty well and hold its length. If you experience cases getting longer, you're treading on thin ice. that extra brass comes from somewhere.

Hoot

FWIW, this is the first time that I've heard of the 50 B&M Super Short. Pretty cool IMHO!

[coyote wacker]

FWIW, this is the first time that I've heard of the 50 B&M Super Short. Pretty cool IMHO!

Michael McCoury is the inventor(Father) of B&M Cartridges all guns are chambered on Winchester Model 70's CRF guns only only way to get one chambered is at SSK Industries he will help you with dies and brass if needed....all are based on WSM or RUM brass...

I have several rifles 9.3 B&M, 458 B&M and a 50 B&M SS.....

For those that like large bore rifles and shorter barrels these are the ultimate proven guns and cartridges....


https://www.b-mriflesandcartridges.com