i'm not an expert by any means, but it seems to me that if you need an extra mag for a back-up gun , then you REALLY did something wrong. if you go through your primary mag, second mag for primary gun, empty the BUG, and have to reload it, you are clearly in over your head and should consider the "beat feet" defense. i carry a spare mag for my primay gun and thats all. i'm not trained with a knife so it really doesn't do me much good. 22 rounds is more than i'll probably ever need. heck the 10+1 is probably more than i'll ever need. i hope.
Bobby