Chap

Knight Disc Extreme and Elite are capable of shooting 150 grains T7 loose with a given projectile.

BH is a progressive burning smokeless powder and does not create the peak pressure that T7 does. T7 burns a consistant rate which is fairly fast as compared to BH. BH in effect does create pressure in the barrel for a longer period of time than does T7 and thus creates a greater velocity. Acting much like real smokeless powder with a longer burning rate such as 4064 vs 4350. Another characteristic of BH is that it is much more efficient with heavier projectiles.

With Grouse using a 200 grain projectile - BH really does not realize it's full potential and the pressure is significantly less than say shooting a 300 grain projectile.

I hope this makes some sense - I have it semi-clear in my mind but I am not a very good writer... I am sure Tom will/can correct me if I am wrong.