The Bren mag holds ten rounds (a lot of books that discuss the Bren Ten quote 11 or 12 rounds, but that's incorrect). From a collecting standpoint the Bren Ten wins hands down. It's an excellent design and just a beautiful gun. There were, however, various "teething" problems that due to the company's short lifespan were never fully worked out. So, even though it pains me to say so, if I had to choose between the two and it was going to be a daily shooter I would pick the S&W 10xx series without hesitation. The S&W 10mm pistols are, in my opinion, some of the most underrated guns out there. They are more than strong enough and very reliable, and on top of that they are still resonably priced considering they haven't been produced for almost ten years now. My current CCW gun is a S&W 1086 and I have every confidence in it.