Markings I can't identify

[Garanditis]

Gentlemen, I was surprised to find two stamps I'd never seen before on my Garand this AM despite the number of times I've cleaned it after each shooting session. Can somebody identify these markings? One is most likely a proof (a 'P' on the underside of the April 1944 receiver) and the other one is just a stamp I've never seen before, also on the underside of the same receiver. The stock on this rifle is marked 'RRA' indicating it was an RRA rebuild but in general, this rifle is a mix master. Anyways, my question is about the markings. I'll attach photos.

[Phil McGrath]

I agree the "P" is just a passing inspection stamp, the other is anyone guess but it could be unique too RRA I would ask others that have RRA rifles if they too have a similar stamping.