Just picked up and nice 3rd Gen Glock 20 in trade last night. The 10mm round has always been one of those oddball rounds that I really wanted to get in to. I also acquired about 120 round of ammo with the trade. Some Federal hollow points, some Georgia Arms target round and some Prvi hollow points. Looking around online, 10mm seems to be about the same price as .45 ACP just not to easy to find around here. (Virginia) I can pick it up at gun shows with no problem. On to the question at hand. I was reading a thread in here that was posted a few months back. I think it answered my question but I really want to be sure. Can I run a regular old 40.S&W round through my factory Glock 10mm barrel safely??? If so then that just made my damn day!!!!!!! I would be able to save a bit o' money and buy some Underwood ammo for self defense and use the .40 S&W for target practice. Plus I can reload my spent .40 and 10 mm brass!!!