It is never bad to clean your rifle. Usually the solution to the problem is the simplest possible thing. i.e. My daughter calls and says, "My car won't crank over", I say did you check the battery terminals? That was the problem.
I bought two boxes of Winchester T22 match rifle ammo last October. They shot terrible printing 1" plus groups at 50yds in a rifle that usually shoots 0.300" or so. And I had multiple misfires and one case stuck in the chamber. After shooting about 20rds, I stopped and set it aside. Either it was poor manufacturing or the ammo had been poorly stored. It was clean, and bright. No signs of water or wear and tear. I do not know their lot codes to determine how old it is, but I have ammo that is 20yrs old that shoots fine. My guess is that it was stored in a outdoor storage space and exposed to excessive heat over time. That is hard on ammo. But, IMHO Winchester also seems to have more quality control problems than most ammo suppliers.
Go ahead and clean the gun but if that does not fix it, try some good ammo that you know works well in other guns. If that does not solve the problem start looking at the firing pin, etc. No, on second thought I would switch ammo first.
Irish
