Originally Posted by
Son
Since we began looking at the "P" a while back, I've gathered heaps of pics of the "P" marking on barrels. There seems several different stamps have been used and the position of the mark varies also. One thing they all have in common is the presence of protective paint (or the remnants of) on the barrel and usually action, under the wood line.
On the topic of the R meaning replacement barrel, the date of manufacture and the serial number stamps look, from what I can see in the pics, to be identical in shape and application. I think the barrel is original to the build.