Thread: 308 Subsonic powder alternative to Trailboss

For Cast bullets, Red Dot, Green Dot have been widely used in 30 cal. ADI have published data for AS30N, a Shotgun/Pistol powder. Some other Shotgun powders are very close to AS30N, which is very close to Red Dot. 10gn is a useful start point to work up or down from. Subsonic tends to run below 10gn. Below 10gn, any such powder, be sure projectile leaves your barrel. 7.0gn is kinda getting down there. Its also useful with cast to consider 13gn as likely to be a max load. Generally 13gn in 30 cal and 303B will give you between 1400 and 1800fps. Accuracy tends to deteriorate quickly after 1400fps. Higher velocity in cast is feasible with accuracy but tends to require a specific combo of lead hardness, gas check and bullet lube. Twist rate really comes into play. Starting out I wondered why my 303B was not registering any hits on a large piece of cardboard at around 35m. The big Grey cloud between muzzle and target turned out to be 215gn of too soft lead vaporizing at something around 2200fps over a 45gn charge of RL19. A published load for a Woodleigh lead bullet BTW.

Anyway. Lots of options for you. While you get your sub load sorted, try a load around 1200-1400fps. You may be surprised how quiet, accurate and hard hitting it can be.

Have fun.