Swept. Under bright light with a magnifying glass, it still looks like a capital P, not R. I can find no other markings on it. Machining is a bit rough. It has the large gas hole that would line up with hole in the left side of the receiver ring in A3's. There are no wear marks to indicate it has ever been used. It's apparently a war-time replacement bolt made by an outside contractor like Bonney Forge, etc.