My usual is the Kimber Custom LW 5" with this OWB can be worn CC with over shirt, or OC without a cover.. both legal here in Montana.
My second choice would be the Sig P220
and my third choice would be the XD 4", all of course in .45 ACP.
I wear this concealed under an overshirt or vest... If it's pretty warm outside, I have an IWB for wearing with a t-shirt. I don't OC unless out in the great outdoors.
I see I had a typo, I meant change not chance :D, but that will remain to be seen, to see what kind of groups I get with XD 4" vs what I get with my 1911's.