Last year I attached a mod to my R93 in 308. I was using Blasers`s own brand CDP ammunition. After the first shot, the bolt was stuck firmly and would not pull back. It took 5 minutes and some force to eventually free it. No more shots were fired until March of this year. Today I tried some Normal 150gr Jaktmatch rounds and there was no issue whatsoever and the accuracy was superb. I tried Privi 168gr HPBT and the bolt was quite difficult to pull back but accuracy was still superb.......the guy in the next lane was a reloader and he examined the shell....no sign of pressure whatsoever.......Would be grateful for any suggestions as to any causes and possible solutions as I am sitting on quite a lot of 165gr and 168gr ammunition!