a few years back there was an old guy that had one close to me. His was a real STGW44 (milled reciever) as I was told (I never actually saw the rifle). I heard him shooting it a couple times and it just had it's own sound, but he was always gone by the time I got to the range. I did manage to pick up a few dozen cases off the ground, and gave most of them to buddies of mine that collected brass. Never seen anything like item, and nobody else had as well (about 30 years ago). Cases were copper plated steel, and the head stamp was very oddball looking. I took a half dozen cases into the platting room and had the copper stripped off them to get a better look at them. They were German!
99% of all STGW's are 45's and not 44's (even the NRA guy is incorrect). The 45's had the stamped reciever, and went into production sometime in 1944. Sussposedly the STGW45's were used in the very early days of Vietnam by the VC, but never saw any evidence. I do know they had used a few MG42's as well as some others using new manufactured Mausers off the same pattern.