Don't let rumors become a reality. I shoot with plenty of people who use reloads in factory stock Glocks, and have never heard of such issues (until I read threads like these of course)
There may be issues with relatively soft cast lead bullets that can foul a factory Glock barrel's polygonal rifling faster than they would the barrels of most other handguns, causing a sharp increase in pressure after a certain point (and quicker than most would expect). There are people who shoot unjacketed cast lead bullets in Glocks with their stock barrels, but either the lead is hard enough to keep things safe or they thoroughly scrub their barrels after every session. The notion that one cannot shoot cast lead bullets in Glocks at all is a myth, but at the same time there are real reasons to be cautious and know what you're doing (or just have good luck ).
I thought the modern Glocks got a fully supported chamber about 2 years ago?
Yes, apparently Glock reconsidered and now their .40 S&W barrels have fully supported chambers. This doesn't seem to have impacted reliability noticeably, and it doesn't for other guns that have fully supported chambers.
I have seen pics of a S&W M&P .40 that was blown up reportedly firing reloads.
Make no mistake about it--ANY gun can blow up as a result of poor reloads, or even with a perfectly loaded factory cartridge that suffers from bullet setback from repeated chambering, for example.
What's different about Glocks is that originally their stock .40 S&W barrels had chambers that left quite a bit (in the view of many) of the case unsupported, and this apparently lead to a slightly increased risk of case failure, one specific manner in which pistols can explode in one's hand. The bulges visible in the cases of cartridges fired in .40 S&W Glocks indicate additional stress, and there is no denying this fact. But despite this fact, using new brass from factory-fresh rounds, the additional risk is practically negligible. It only became an issue of note when using reloads, even good ones, because brass can only take so much abuse before failing. The issue was still blown out of proportion, but it was an issue, and it was serious enough to cause Glock to modify the barrels, and now it's not an issue at all in new Glocks.
I own 2 glocks (a .40 and a .357 Sig) and the chambers don't seem to be any less supported than any of my other pistols, although one was purchased in 2000 and the other in late 2007, so Glock may have already corrected the problem...
It was a problem and it has been corrected. The M&P's chamber, by the way, has always fully supported the cartridge case, although I'm sure that a few have blown up for various reasons, and it still happens to Glocks, too, but at least it's not because of a lack of case support for either of these guns now.
I'm not worried about my Glocks blowing up and I wouldn't worry about a Smith/Sig/XD/HK or any of the other polymer guns from reputable manufacturers.
Well, I still take steps to avoid bullet setback, especially since I use 180 grain .40 S&W rounds. My rather conservative rule (I think) is that no defensive round is chambered more than once before it is set aside for range practice, and that no FMJ training round is chambered more than once, period. I'm probably going overboard here, but it doesn't hurt much while an exploding pistol does.