1911 Frame Markings, etc.

I have this 1911 frame with marks: P 0xxx PAC.Mdsto.CA on right side where s/n goes and S A M RP. on left side just above mag release button. Does anyone know who that maker is? Any info appreciated. It is new mfgr and seems like a good product. In assembling it with old original 1911 parts I had to open up the mag latch hole about .005" and had to make clearance, maybe .010", where the sear straddles the disconnecter. Slide rail fit was good. Various other fits seem a little looser than the original frame. Mike measurements between frame holes pretty close. Was unable to properly measure the relationship of the vertical disconnector hole to other cross-frame holes which may account for the interference at the sear. This is my first experience inside a 1911 and thought you 1911 specialists might be interested. Piece test fires satisfactory.