Check the muzzle pressure values predicted by QL. The bullet's exit essentially uncorks a very high pressure bottle. The higher the pressure, the louder the "POP!" when the corks comes out, just like a wine bottle.
It effects the muzzle flash and can also effect accuracy too, because the bullet is directly effected by the muzzle blast.
It also has a dramatic effect on recoil. Use QL to find a powder with lower muzzle pressure and check it's recoil calculation, then check one with a much higher muzzle pressure but similar velocity.
One of my favorite features of QuickLoad is its ability to predict low muzzle pressure powders for short barrels.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.