March 15th, 2017, 10:18 AM
Join Date: Mar 2009
Location: Endwell NY
Originally Posted by politici ad mortem
Wait a second, if all the gas is trapped behind and driving the projectile prior to escaping through the gas port in the barrel, the only way to affect that pressure would be with more powder behind the round, wouldnt it?
I don't understand what you are asking about ...
The 'type' of powder affects the barrel pressure as the bullet travels from chamber to muzzle.
A 'fast burning' powder produces a quick 'burst' of high pressure that only lasts a short time, so the 'barrel pressure' decreases rapidly as the bullet moves forward.
A 'slow burning' powder produces a longer lasting high pressure period, so the pressure in the barrel stays high even as the bullet moves forward.
For gas-operated rifles it's necessary to have the barrel pressure be within a useful range when the bullet passes the gas port.
Endwell NY USA