Between 1921 and 1972, Remingtons can be dated by the barrel code. 2 or 3 letters stamped on LEFT side of barrel may a half inch forward of receiver- you may need a good light and a magnifier. Link to interpeting: Remington Dates of Manufacture
Ref: dry fire burr- good advice given. DO NOT just remove the burr- you need that metal put back where it came from. Brownells ironing tool is good. However, I am a shade tree hobbyist, and never bought one. I have used a Stanley nailset, along with a small fat tipped punch to do the deed. gently and carefully.