Without seeing the underside of the lock bar, it would be hard to say for sure that it is a type III SA. but looking at that last shot of the side edge, and how it looks almost like a casting mark, that is typical SA. Between that and the squared ends, I'd say type III SA. BUT, I wouldn't change a thing. Even if it is, who knows if it is or isn't an original. Sure would be time wise. And some WRA rifles have been observed with unmarked late follower/slide assemblies (which most equate to post-war SA rifles) and there have been some WRA buttplates found on SA stocks. All I'm saying is that the wear and finish looks consistant. I wouldn't touch it. In my book - and that isn't saying much - I'd say original. Who knows what will be turned up tomorrow as to how these things were built and using what parts. I'd sure like to see some shots of the gas lock screw, particularly the inside holes. Do they look flat on the bottom of the holes or are they beveled? Nice rifle for sure!