This is probably going to sound pretty stupid but here goes. I'm looking at buying a Kimber 1911. I see that some of them come with 7rd mags and some with 8rd. From the specs I can find on them, they look to be the same size physically. The question is this. Will a 8rd mag fit in a gun designed for a 7 and vice versa? What exactly is the difference in the two guns? The 2 in particular I'm talking about are the Kimber Custom II and the Kimber SIS Custom.