With the Accura (or similar), if I had such a problem, backing out the firing pin retainer would probably be the better way to go so long as it didn't interfere with action operation and the retainer threads still had sufficient engagment. It would be easy enough to make a shim to go in behind the retainer but it might not be easy to achieve the right thickness. Bellm sells such shims for the Encore system and those might be fitted easily. If a .001" or maybe .002" wouldn't do the trick, I wouldn't mess with that either.

I want my breech plugs always snugged up but I will admit to having experimented with them just as Semi describes. In a rifle where a shim would work safely, that's the route I would take.