I've never seen or talked with anyone who has actually seen a Glock damaged from shooting lead.
Has anyone here seen this maybe-mythical beast or observed such damage?
I was in the clubhouse when a shooter came in with the pieces of his Glock. The armorer pointed out that the bore showed severe lead fouling. The shooter, though otherwise uninjured suffered some memory loss. He couldn't remember what kind of ammo he had been shooting.
After he left, his friend acknowledged that the ammo was lead bullet reloads. Of course, it could have been a reloading mistake, not a result of the fouling. It's hard to say.
Some years ago, either on TFL or THR, a member posted about blowing up his Glock 19 after shooting a box of lead bullet ammo and then following it with a single round of jacketed ammo.
MarkCO, (Mark Passamaneck) a member on TFL and a co-author of "The Glock In Competition" blew up one of his Glocks using lead reloads. Being a forensic engineer, he studied the issue and determined the cause. He went further and tried to develop a rule of thumb that would allow a person to safely shoot lead through Glock rifling. He found that harder bullets did show less leading, but he was unable to find a recipe that would completely preclude the problem. He found that the factors involved would not allow him to develop a rule of thumb that would allow the safe use of lead bullets in Glock rifling. He stopped shooting lead bullets and started reloading plated bullets for his Glocks.
There are a few issues involved.
The nature of the Glock rifling can make leading difficult to detect.
For whatever reason, even apparently identical Glocks will lead very differently when shooting the same loading. Passamaneck experimented with two outwardly identical Glocks using the same loading. One, after having fired only 75 rounds, exhibited twice the effects of pressure increase as the other pistol did after having fired 300 rounds. That's double the effect from 4 times fewer rounds. It's not so much that every single Glock out there will lead badly and blow up after a box of ammo--it's that it's not possible to tell ahead of time how badly any given Glock will lead-foul.
Shooting leaded rounds followed by jacketed rounds can be a problem in any gun. Allan Jones, of Speer recommends against it, stating he has seen many guns damaged by the practice. Beretta states that it should NEVER be done (their emphasis) and places the warning in their pistol manuals. I suspect that this problem (combined with the difficulty of detecting leading in Glock bores) is a big part of the reason Glock finally started warning against lead bullets.
By the way, Gale McMillan (noted barrel-maker & benchrest shooter) provided a general warning about leading in polygonal rifled barrels. If you believe that he knew what he was talking about, it would seem that this problem isn't specific to Glocks.
If you've been shooting lead in your Glock pistol without incident and you keep doing exactly what you've been doing, you're probably going to be ok. If you change anything there's no accurate recipe for determining if the change will cause a problem or not. Passamaneck states that he had about 20K rounds of lead bullet reloads through his Glocks before he finally pushed things a little too far in one shooting session and blew a pistol up.
Glock says not to but they also say not to use reloads.
This is another complication to this problem. Because the warning not to use reloads is very common (and very commonly ignored) many people assume that it's always ok to ignore it. They feel that it's just the standard lawyerese that all gunmakers put in their manuals. In this case, it seems that there might actually be a little more to it than that.
