I had a full size SR9 and I bought a Serpa holster for it. I seem to remember it slid in easily with a nice audible click. I just got an SR9C and it does fit, but it seems to kind of mush in there. It does lock in, though. Is the Serpa holster for the fullz size the same for the compact? I know it will be longer to accomodate the longer barrel.