Yes it happens because the gun used was fired with jacketed rounds and not cleaned correctly before firing lead rounds. If polygonal rifling caused lead induced failures then lots of rifles with much higher chamber pressures in the 1800s(whose barrels were hammer forged with polygonal barrels, just not called that in the day)that had nothing other than lead rounds would have been blowing up left and right. show me a study that shows a NIB Glock that leaded a barrel right out of the box. Any failure due to lead exists between user and interface. That being said if you don't trust using lead, don't use lead. I have never had an issue, but any warning is a Good warning when it comes to firearm safety. I tend to error on the side of safety, even if my post seem to say other wise.
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