I've recently had an issue with my CZ452 .17hmr, cycle the bolt, squeeze the trigger and click, no fire?!?!? Hold it in a safe direction in case it's a hang fire, nope not happening, lift the bolt and recock the bolt without extracting the round, drop the bolt squeeze the trigger and bang it goes off second time round.
This happened with the next 5 rounds, all failed on the first and went on the second attempt. Anyone who, like me, strips and cleans the mod off their hmr after each outing will know what a dirty round it is, filthy.
So it got me thinking maybe the firing pin was dirty and not striking properly, with no enough force to ignite the primer. I stripped the bolt, cleaned it up and lightly lubed before wiping it almost dry with kitchen roll. Reassembled I took the rifle out and stuffed 3Nr 5 round mags through it without issue, problem solved.
So I would say cleaning the bolt on your hmr every 500-750 rounds isn't a bad idea.
Good advice, but relevant to a different type of failure -of the firing system, not of the ammunition- and one which can affect a gun in any calibre.

