.240 PSP bullets

awinds

Have .240 PSP with 24" barrel, 1-12" twist.
Looking for experience with heaviest bullets that will stabilize
with the 12" twist.

nononsense

awinds,

Barrel makers generally limit a 1:12" twist to bullets that weigh somewhere around 85 grains. Reversing a modified version of the Greenhill formula indicates that a bullet with a length of 0.738" is the longest bullet that will stabilize in this twist.

But and it's a big but, I've shot short jacketed 85 and 90 grain lead/copper bullets in a 1:12" twist like yours and did just fine. You need to think flat bases and lead cores with no plastic tips, hollowpoints, mono-metallics or exotic secant ogives like the VLD's use. Some folks have an axe to grind with regard to the Nosler Partitions but I've had great success with them for a long time. The Lapua Megas, Hornady SP's and similar flat base lead core bullets will work nicely also.

That's the basic guidelines for this cartridge and other than that, you'll have to buy some bullets and shoot tests. You might find some exceptions with a couple of other bullets and your barrel but this is what I've seen work.

Best.

sandwarrior

awinds,

Not knowing what exactly the .240 PSP is I would say no problem to 100gr. bullets if pushing them 3000 fps or so. If the case won't reasonably make that then 80-85gr would be more the norm. When Remington originally came out with the 6mm Rem(then .244 Rem) it was a 1-12" twist and it would just stabilize 100grs at max or near max velocity. They designed it for 80 gr. bullets at 3200 fps., for which it had plenty of twist.

Like nononsense pointed out the shorter the bullet the easier it will be to stabilize it, as twist is more dependent upon length than weight. -good luck

awinds

Thanks, Nononsense and Sandwarrior.
That's just what I needed to get me started.
I'll start with 85 gr, then 90, and then 95.
Will try several compatible powders and shoot and chrono all.
Sandwarrior, the .240PSP is an enlarged and fireformed 6mm Rem.
Thanks again, guys.