Photos from Dan's GH 20

[J.B. Books]

I am not engineer and have no experience or training in the physics and engineering involved with a barrel burst. What I find counterintuitive as a layman is the amount of pressure required to burst a fluid steel barrel is around 30,000 psi per Sherman Bell's destructive tests. How is it that a shot charge and wad being pushed by a force between 11,000 and less than 30,000 psi wouldn't dislodge and send a thin plastic base wad stuck in the bore out the muzzle before it reached a level of barrel burst pressure? Serious question looking for an answer. Perhaps the answer is the pressure builds faster than the ejecta moves but I don't know that.

[ArtS]

Originally Posted by Pete Lester

I am not engineer and have no experience or training in the physics and engineering involved with a barrel burst. What I find counterintuitive as a layman is the amount of pressure required to burst a fluid steel barrel is around 30,000 psi per Sherman Bell's destructive tests. How is it that a shot charge and wad being pushed by a force between 11,000 and less than 30,000 psi wouldn't dislodge and send a thin plastic base wad stuck in the bore out the muzzle before it reached a level of barrel burst pressure? Serious question looking for an answer. Perhaps the answer is the pressure builds faster than the ejecta moves but I don't know that.

Remember that smokeless powder has a pressure/burning rate curve. As mentioned, Bells bursts were open tubes. If a wad is stuck a couple of inches in front of the chamber, it is at the normal max pressure point anyway. If the obstruction holds even for a short time, the burning rate can go extremely higher and reach catastrophic levels before the wad even has time to move. Dean's inertia effect. It likely did move down the barrel quickly, just not as quickly as the pressure increased. It's the fatal flaw of a progressive powder; rate of pressure increase is dependent on the pressure.