Stevens 305 missfiring

I've got a Stevens 305 22 mag that is missfiring now and then, I've tried differnt ammo, disassembled the bolt and cleaned it polished the firing pin and groove. And it still misfires 1 in 5 shots. The sear has a notch in it where it contacts the bolt and my 93 doesn't. The notch doesn't look worn but machined from the factory. I even added spacers to compress the spring for more tension and a harder primer strike. Does anyone else have or had this issue and if so, what did you find the cause and fix to be . Thanks

Will it fire the cartridge with a second strike? Your FP spring may be week.

Chamber might need cleaned, crud in chamber can cause your problem.

Yes it will fire with second strike, I was talking to savage. They beleive it is a spring or firing pin issue, so they are sending me the new parts for free. Can't beat that