The M10 receiver sheet metal is heavier gauge. I think they stay together a bit better than M11's. The 9mm version is much better than the 45 ACP version but the 45 ACP can be converted to 9mm and 45 ACP might be a bit better if a suppressor is used. a full magazine of 45 ACP heavy !! Carrying a few of them will leave dents in ground where you walk. I like the way the 9mm M10 handles campared to the same in 45 ACP. At one time the M10 9mm magazines were hard to find but these days there are plenty of the Walther MP magazines they use. At least more than what used to be around. This is one of the best 9mm magazines. The M11/9 is suppose to be more refined and lighter weight. They used to cost a lot less. They aren't a bad design , I just prefer the M10 in 9mm.