I ask because right after I bought my M&P45FS I found very few holsters listed for it specifically. I heard that the Glock 20, 21 holsters fit, so a while back I bought a Bianchi Shadow II Model 7 (OWB) listed for the Glock 20, 21 and it does allow the M&P45 to fit all the way in, short of the last 1/4" at the muzzle. I wet it then swelled it a tiny bit and it fit, then I found the thumb strap tries to go over the beaver tail and not over the back of the slide. grr-r-r... So I trimmed about 1/2" off the thumb strap to fit around the beaver tail and now it fits fine. I carried it in that holster infrequently OWB but concealed.
I mostly carry IWB and since I got my 4513TSW I don't carry the M&P very often.