Since you mentioned blow-ups I might as well relate an experience of my own. Although it happened with a rifle, it has some similarity to your mishap
(and MegaMag's S.E.E "myth"
)
Back in the late seventies i bought a Swedish M96 rifle. Later I also bought several hundreds 156 grains 6.5x55 Danish mill surplus ammo
(M96 was our military rifle for a few years after the war) The rifle appeared brand new, and I doubt it had ever been used, much less fired.
Well, I enjoyed the rifle and shot it from time to time. Then one day while studying my "bible", The Book of Rifles, I came across a warning
in a chapter of Swedish rifles. It mentioned a specific lot of Danish mill surplus ammo in 6.5x55 which had caused several blow-ups on Danish shooting ranges.
The headstamp was clearly described, and (you guessed it) it matched my cartridges!
That gave me something to think about, I wasn't rolling in money at that time and didn't fell like scrapping the lot.
The book said the problem was caused by fouling due to too the jackets being too soft, and I decided to try to reduce the load a little and maybe avoid fouling.
I pulled the bullets from four cartridges, weighed the powder and loaded the cartridges again with a 10% reduced load (weighing each load on my Ohaus 1010)
and, together with a couple of friends, went to test the load.
The first two rounds fired as expected, and I remember telling my pals that the load seemed quite mild for a 10% reduction. Then I fired the third round...
I can't remember hearing any boom, but I remember distinctly the feeling of warm blood running down my nose.
To make a long story short, here's what had happened: The bullet never left the barrel. It was lodged firmly in the throat of the chamber with the rear of
the bullet deformed and expanded (I later tapped the bullet out from the front without using much force) Since the pressure had nowhere to go, it went
out the rear of the case, into the firing pin hole and blew the firing pin rearwards with such a force that the 1/4" pin snapped and the rear part flew back
hitting the knuckle on my thumb (four stitches) then hitting right between my eyebrows (two stitches) before taking off for places unknown.
After a visit to the emergency room, and a cock-and-bull story about a bench drill job gone wrong, I was non the worse for wear, but a little shaken...
When I later examined the rifle, it was obvious that the reason the blow-back had such a disastrous result was the vent holes in the M96 bolt were too small,
compared to the two large slots in a M98 bolt it's obvious that Mauser learned something between model 96 and 98.
I replaced the parts in the bolt, including the mainspring that was reduced to half length, "sporterized" the rifle, and continued to use it for hunting for the next
twenty years (and I enlarged those vent holes!)
I'm not quite sure what happened that day back then. But I'm sure it was the same thing that had happened on the other Danish shooting ranges, and by reducing
the loads I had actually increased the likelihood for the blow-back to happen.