This magazine is unmarked and is probably one of a kind.
The magazine is probably made by a very skilled amateur. The magazine body barely shows any traces of welding and the finish is very good. However the holes in the side of the body are not alligned properly and the holes are smaller than usual.
The magazine floorplate and the inner parts are very amateuristic made and of low quality. I should note that the magazine function flawlessly and the person who made it did a very good job!