Don, is it true that, given equal obstructions, one nearer the muzzle is more likely to cause a burst barrel, than one nearer the breech? My reason for asking is that it would seem that the more air that is trapped in the barrel, the more severe the air hammer will be.
Stan, the "hammer" is a gas hammer within the propellant gas and is not within the air in the barrel. When the wad/pellets encounter an obstacle, they slow down. If they slow sufficiently, powder gas will "pile up" behind the wad and will dramatically increase in pressure, that is, hammer. If the obstruction is sufficiently durable, shock waves may reflect back and forth within the barrel (IMO the source of riveling).
DDA
SRH
