Home Forums Hunting & Shooting Hunting Rifles Barrel length and noise

To elucidate on what DigitalDan said, muzzle blast is part sonic crack and part muzzle pressure. Here is a standard rifle pressure curve, obviously different powders give slightly different traces but with typical centerfire rifles pressure rises fairly rapidly and then slowly lessens as the bullet moves down the barrel (more volume for the gas). Instead of using time as the X (bottom) axis think barrel length, the more length - the farther out you are on the pressure curve - the lower the pressure when it is released into the atmosphere.

Slow powders and short barrels are the kings of muzzle blast since the pressure curve stays higher longer, ie. that "tail" stays up higher on the graph as it extends to the right, longer barrels and quicker powders will put the pressure curve at a lower point when the bullet exits.





Engineers and physicists will forgive my non-technical explanation but hopefully the gist is clear.