BEST SHAPE BULLETS FOR SUBSONIC 308

First order relationship: stability = f(bullet length & angular velocity). Of course, angular velocity is a product of rifling twist and forward velocity.

- Base shape is a pretty small contributor to length in a given weight.
- .300BO solves this with 1:8 rifling.
- Your easiest solution is probably a lighter bullet

Just curious: what are you using for powder to be subsonic in that huge case?

Stability is driven primarily by length and angular velocity (velocity divided by twist). You are stuck with your 1:10 twist and a max velocity of ~1050 (if we assume you want to stay sub sonic) so get a shorter bullet for a given weight. Flat base round nose bullets will be shorter than a BT with a long thin ogive of the same weight and thus likely to stabilize at a slow spin rate for a given velocity. I would try some round nose flat base 180gr and see if your gun will stabilize that. Pushing you velocity as fast as you can go and still being subsonic that will help a wee little too.

If I was to be trying to make that load I would be casting around nose Flat Point.
https://bergerbullets.com/twist-rate-calculator/
https://noebulletmolds.com/site/product-category/308-311/308-180-fn-g5