i have a question of which i hope some light could be shed on. My question relates to my 1948 BSA Sportsmans Five .22 cal rimfire rifle. i have shot countless amounts of rounds through it in the past couple years, most acurate gun ive shot. a couple months back it started misfireing 1 in every 10-15 rounds, i sourced another firing pin for it which had been tested and shown working 100% and thus solved my problem. After possibly anther 300 rounds through it over the course of several months it now misfires almost every time. i am using remmington subsonic rounds and i have ruled out the possibility of the ammo being faulty as i have just tested the same batch in a newer rifle and 100% working. i would apreciate any thoughts as to the possibe cause of this dilema. thanks in advance, grant.