Went out this am to do some function firing with my 9VE. Recently I was given some remanufactured ammo in the original box, loaded by a fairly large commercial firm. The ammo was about 20 years old, and the firm is still in existence.
The pistol is about two years old, had about 500+ rounds of my hand loads through it, and had recently been back to S&W for minor tweaking of feed issues. On the 10th round I felt a substantially heavier recoil and gas and particles in my face (had eye and ear protection on). When I looked at the pistol I saw smoke issuing from the muzzle, breech, and bottom of the grip. I also noted that the slide was about 1/4" open and the magazine had dropped about 1/2". I cleared the weapon, and when I opened the slide the fired case fell out. It had blown at the case head for about 1/4 of its circumference, most probably right at the feed ramp cut--as most of the pressure went down the mag well. A quick field strip and inspection revealed no other damage and a function check showed the pistol was ready to go again. However, enough was enough, and I really didn't want to fire the pistol again with ANY ammo until I had a good chance to look at it under good light with magnification and at my leisure. When I did I found the mag catch cut in the magazine to be intact but the mag catch itself somewhat deformed from when the mag blew out. So far I think that is the only damage to the pistol.
I have had some case head separations in the past, witnessed one good blow-up, and seen others with 'interesting' case head separations. Stuff happens. I DON'T shoot others' hand loads, and it seems that this needs to extend to 'remanufactured' ammo as well. I prefer to do my own QC, I guess.
The good news is that the Sigma stood up to this pretty well. Hopefully S&W will sell me a new mag catch; not the old one will probably straighten out with a little persuasion.
Someday I'm going to have to learn how to post photos.