2.5" groups at 50 yds ? That' s terrible ! I have a stock 10-22 stainless Sporter that groups .5" @ 50 yds right out of the box . Is there a problem with your barrel or action ? I' ve gone through up to 12 mags without problems using Federal Gold ammo , and had no extraction problems . By the way , Ruger reccomends against Stinger ammo in the 10-22 , probably a case length issue . Take it to a gunsmith to have it checked , you may have a defective rifle . Chamber too tight ? Sounds like bs to me . He must be shooting loads with too little headspace . He should be made aware that this can be dangerous if that is the case .