I would feel better about the NRA stamping if it had periods after each letter. The fact that it was restamped doesn't bother me much because even rare coins sometimes had duplicate or double stampings. It just means that it was stamped twice- it's not a guarantee that it is fake. But, I know that anyone can stamp letters on anything.

The barrel is an interesting situation. Don't know where it came from.

Thanks for the comments. I'm still searching and appreciate your help. The rear sight is interesting to add to my sight collection.