[Plank Road Farm]

Have asked this question on Rimfirecentral.com but haven't gotten an answer.

What is the distance supposed to be between the firing pin and the breech face?

I have heard that dry firing will damage the firing pin.

Mine does not have any indentations on the breech face that you would expect if it was hitting when dry firing.

Then, why do I have mis-fires where there is no dent in the cartridge rim?

This does not happen everytime.

I know there could be a problem with the type ammo.

I have used Remington, Aquila, and Winchester, all with similar results.

Any suggestions?

[hoghunting]

My first thought would be to pull the bolt and clean the firing pin channel. It might be gummed up with old grease.

[Chawbaccer]

Dry firing will put a burr on your chamber and not allow cartridges to chamber reliably which could be your problem as the energy of the firing pin is being used to seat your cartridge. Clean your gun like Hoghunter suggests, check the chamber for a burr and also clean and check the bolt ways for anything that could keep it from closing completely. Use a dry lube on the bolt race ways and firing pin channel.
Good luck.