I have a SP1 that I bought in the early 80s. I want to get an extra upper for it that I can scope (I have a carry handle scope mount and don't care for it). Looking to go 18 or 20 inch. Will use for plinking, varmints and maybe some deer. More accurate is always better than less, but I won't be entering any long range matches. I have home/property defense covered with a 16" piston operated, aimpoint, quad rail, etc. Looking for just screwing around. Any suggestions?