onondaga
posted this
30 April 2013
http://www.castbulletassoc.org/view_user.php?id=2006>casca:
I recommend you take a good look at Hodgdon Titegroup and what Hodgdon says about it at their site. It looks like the ideal selection for subsonic to under 1,600 fps for the 300 Blackout.
You will need to start at about 3 grains for any bullet weight in that cartridge for near sonic velocity. A chronograph will be needed to monitor your velocities and stay safely sub-sonic if that is what you are looking for.
Hodgdon really brags that this powder lights very well even with tiny charges in large cases. It would be my first choice. I use it with the 300 AAC cast Lee bullet in 7.62X39.
If you want to stay subsonic regardless of altitude and local weather you need to have a muzzle velocity at ~900-950 fps MAX including any E.S.
Warning: I have seen more than a few reports that Trailboss is erratic with broad Extreme Spread of velocity in the application you are looking into. This means that Trailboss works but the bullets shoot all over the place.
Gary