I'd hope everyone pays attention to what Lagopus has posted about that rifle failure.
I'll relate a similar tale that involved an individual shooting a factory 12 ga. 32 gram shot shell that had been rolling back & forth on the dashboard of a pickup truck for quite a while, a few years in the Texas heat & cold. It was fired at a rattlesnake in a modern pump shotgun w/double action bars & it blew the receiver and the back [chamber] portion of that gun up. It was a catastrophic failure & resulted in destruction of the first order. It did not result in an injury, but could have just as easily, IMHO. It is quite likely that the powder in that cartridge had become 'dust' and as such had zero deterrent and an exponetially increased surface area. In other words, the powder detonated rather than burned. FWIW, The dif in defs between burning and detonation in the simplest of terms is the speed or burning rate, if you will.
I've not ever witnessed a blown barrel per se, but I have two double guns with minor swells or bulges toward the muzzle that were likely the result of some sort of obstruction. In both cases it happened when I'd loaned the guns to others. My bad. Neither of them ruptured, nor did they cause the ribs to become loose. Neither swell is noticable when shooting the guns, but both are when looking inside the barrels or along the affected barrel's outside. Both are before the chokes and neither changed the POI or patterns. I have shot hundreds, if not thousands of rounds through them both since over the years w/zero issues & am not concerned about doing so in the least. Greener addressed that issue w/his thin muzzle [.010" barrel thickness] emperical work long before there was an effective measuring devise. Pressures at the muzzle are simply not great enough to distort thin walls. Bonking them and causing a distortion or dent is another matter altogether.
With apologies for the tangent, but perhaps its within the limits of acceptable thread drift.
