The XDm's are fixed, even the new XD's (last couple years?) they feed most anything now, I've yet to have any type not feed reliable, even with .357 Sig barrel and a 9mm in a XDm40, I run various swc's in all calibers(not the Sig),they have been the most reliable of all my autos. Don't know for sure when the "hump" came to the XD, I think just before the XDm's were released.