Misfiring 336

[Contenderizer]

I have a Marlin 336 (35 Rem) that's giving me fits because once in a while it will misfire (always at a bad time, I might add). When I extract the factory loaded round it will have a very slight indentation on the primer where the firing pin struck, but obviously not hard enough to cause detenation. This problem comes and goes, and all the ammo seems to have the primers properly seated. I had a gunsmith look at it and he found some lead near the breech which we both hoped was holding the bolt back (increasing headspace). Unfortunaly, the problem still exists. I was going to send the gun to Marlin, but they want the scope removed which I would like only to do as a last resort. Any suggestions?