Re: .308 subsonic rounds?? How do you do it????
The info on loads here is good, the caveat I would suggest also is (take the can off to try this first if you don't believe me)
Seat the spire pointed boat tails backwards in the case. The CP and CM need to align differently at subsonic velocities for stability. This is why a 175 SMK wobbles but the 180 RN doesn't. It doesn't really have to do with bullet length, it has to do with shape.
Even if your 1:10 twist will stabilize it up close I'm willing to bet that the boat tail first seating style will keep you stable well beyond what it does in "normal" configuration.
If you use the round for hunting, it makes the thing less likely to deflect off a bone and just slam right through it too.