Charlie: You are right - serial 477 - except it is an "a" suffix. The suffix is very faint, but it's there. The gun appears to be a rework of some kind. Doesn't look to be made this way - unless it was made up from rejected parts. The craftsmanship is horrible.
Jan: Serial is above, and you can see the proofs on the closeup photo. It only has the Eagle test proof. No Waffenampts that I can find. Next time I strip it, I'll see if there are some internal proofs. Finish looks real, and it's got some age to it. Bill Drollinger knew about this example from a long time ago, so it's not a new creation. It looks real to me, but it's certainly not the configuration we are all familiar with.