Looking for powder and load for a 10.5" AR15. Bullet is 77gr SMK. Want to get best velocity I can and minimize muzzle flash. Rifle has 5C2 Phantom flash suppressor and am willing to go to a Noveske. THanks.


Arock

Youare not going to affect muzzle blast much on anAR with such a short barrel. Maybe you could get an 9MM upper for it.

Not interested in a pistol caliber. Got some RL-7, H322 and BL-C2 to try. Some guys with 7.5" Kitty Kats are using 4198. That's pretty fast. Folks tell me the 5C2 should take care of the muzzle flash.

Can't speak directly to a 10.5 bbl ... do have a 11.5 bbl and the blast and flash is severe. Shorter should get a little worse. Slower powders will also tend to be worse for flash as the remains free air burns at muzzle.

The flash issue is very much affected by whether or not you can secure a deterred powder ... that is a powder that has been surface coated with nitroguanidine. Acts as a flash suppressant. Most sporting powders are not and make very, very bright flashes. (Was particulary true of Accurate Datapowder 2200.) Surplus powders are probably the only ones that may have such a coating.

Even so, remember that blast with be severe with such a short bbl regardless of the brightness of the flash.