I would like some information confirmed. I have the honor of possesing my father's Remington Rand .45 serial number "NO 2057006". It also has a proof mark just below the slide release "FJA", a "P" under the magazine release, right side of trigger guard has an "A" and "H", left side triggger guard a "3" towards the front. There is also a faint proof mark that looks like a circle with two cannons crossed on the right side just rear of the top of the grip. Are these proofs an indication the gun was rebuilt at some point?