Rem. Rider #9 (Mod. 1902) ?? safe??

My neighbor has an old single bbl. Remington shotgun, side lever cocking, auto eject, I believe it is a Mod. 1902 what was called a Rider #9, ser. is 1260xx. He would like to use this to learn trap shooting at our club, please don't suggest 'better guns, etc.' he's a poor young guy, minimum wage, couple kids etc. this is what he has! My questions: is this safe to shoot trap loads (3dram 8shot) and anyone have an age estimate. Only serial # traces I could find start at 1921, I'm sure this is older. (It's a 12 ga.) Buttstock is kind'a a mess, any suggestions where we could find replacement?