450 bushmaster dirty barrel question

[Cantshoot]

Just bought a Cva scout 450. Shot it today for the first time and the barrel was filled with powder after the first shot. New to straight wall cartridges and never been around anyone shooting one. Is this normal for the 450? Shooting 300 grain federal power shock. Pic doesn’t really do it justice but best I could get.

 

[RockAndSage]

That would be some really strange powder, given the shapes.