I've been shooting a new Tikka T3 lite in 223. The first group shot thru this barrel (after 2 sighters) was a 5 round group less than 0.800". No signs of pressure or any other kind of problems. This past weekend I decided I wanted to mess around with Trailboss, running 8 grains under a 55 grain FBHP. It consistently put 5 rounds into less than an inch:
After the 4th or 5th round, I noticed that the bolt had some resistance to opening. I could turn the bolt open, but when I went to pull the bolt back it was stuck. I tugged the bolt handle a bit harder and it came loose and ejected the case easily once it broke free. I did not have to really reef on it, it just was a bit "stuck". I should have inspected the case head a little more than I did. I didnt notice the primer until a bit later. SO in this picture below, the case on the far left was the one that was "stuck". The other cases didnt reallly stick but had a bit of resistance to pulling back. You can see the first one has a teardrop shape to the primer dent and then a scratch from there out to the edge of the primer. The following 4 rounds each have a light scratch where the firing pin scratched from the dent out to the edge of the primer.
THis would seem to tell me that the firing pin isnt retracting and when the shell ejects it is scraping. I havent had any time to mess around yet to see if i can see why this is happening, but was hoping one of you guys knew what would cause this to happen.