Recently replaced my Tikka 595 in .222 with another from an SD forum member. I've only shot a dozen or so rounds,but every one has a slight flattening on the mouth of the fired cartridge,rather than being almost perfectly round. I at first thought they had been bumped whilst rattling around in my bag for a few days,but every one is the same. Ive shone a light into the action but can't see anything that might be to blame. There is pitting on the bolt face and the firing pin is quite rounded which suggests to me a high shot count,if that makes a difference.
What could be causing this?