The Firing Line Forums - View Single Post

HSMITH · June 5, 2005, 08:30 PM

I agree with WESHOOT2. I have seen flash vary from gun to gun with the exact same ammo too. Most of my experience with this has been in 45 acp, 357 magnum and 9mm, and I'm sure on a very limited scale compared to WESHOOT2 but it was readily apparent. I've also not done much testing in true darkness, but rather in 'low light' conditions.

I've been able to draw only one conclusion I have any confidence in, and that is in regards to 357 magnum. A gun with a tight throat, B/C gap, and tight bore will flash less out the end of the barrel than a gun with a looser measurement of ANY of the three items above. If it is looser in two or all three measurements it might breathe fire where a tight gun is pretty low flash shooting the exact same ammo. My conclusion is that efficiency of burn is the real key, in one gun the bullet is held more tightly and pressure builds faster, possibly higher as well but I don't have pressure testing equipment, with this pressure coming on faster the powder is burned more efficiently and more completely. Another observation that seems to bolster my theory is differing amounts of unburnt powder or powder ash left in the barrel after the gun is shot. The lower flash guns have less unburnt powder and less or finer particles of ash.

June 5, 2005, 08:30 PM	#10
HSMITH Senior Member Join Date: June 21, 2002 Posts: 2,019	I agree with WESHOOT2. I have seen flash vary from gun to gun with the exact same ammo too. Most of my experience with this has been in 45 acp, 357 magnum and 9mm, and I'm sure on a very limited scale compared to WESHOOT2 but it was readily apparent. I've also not done much testing in true darkness, but rather in 'low light' conditions. I've been able to draw only one conclusion I have any confidence in, and that is in regards to 357 magnum. A gun with a tight throat, B/C gap, and tight bore will flash less out the end of the barrel than a gun with a looser measurement of ANY of the three items above. If it is looser in two or all three measurements it might breathe fire where a tight gun is pretty low flash shooting the exact same ammo. My conclusion is that efficiency of burn is the real key, in one gun the bullet is held more tightly and pressure builds faster, possibly higher as well but I don't have pressure testing equipment, with this pressure coming on faster the powder is burned more efficiently and more completely. Another observation that seems to bolster my theory is differing amounts of unburnt powder or powder ash left in the barrel after the gun is shot. The lower flash guns have less unburnt powder and less or finer particles of ash.