10mmdoes nothing .45 ACP cant do, for less cost,if you just load the .45 properly. .45 Super cases are ZERO longer or thicker than good .45 ACP cases. So if your .45 has a fully supported barrel, and you load it right, you can have the same level of power on tap, and your gun, ammo, mags,components all cost less than they would if you went with the 10mm, and you can get much less expensive "remanufactured" ammo that's a lot easier onthe gun and on you, in .45. You also don't have to swap out the ejector when switching from .45 to .22 lr. You will if you start with a 10mm,with the exception of "one fits all" Spld ejectors.