I hope someone can help me as i seem to be geting no were,OK I have a nesika 243 AI with a Krieger barrel 1 in 13 twist I use 68 or 70 gr Berger bullets I have put a fair few rounds through this rifle now over the past 2 years but the accuracy has dropped of terrible,as far to say its like a factory rifle using factory ammo,I have done all the useual check seating depths chasing the lands ect I have even had it re crowned,I have had a look with a bore scope and theres heavy fire cracking but the rifling still looks in good order not but not being a gun smith I dont really know what to look for,Personally the rifle gone from banging 10 shots into 1 big raggy hole to not being able to shoot a clover leaf,which this rifle combo should do all day long,Do you think I need a new barrel ?? Also its coppering up really bad and takes a lot of cleaning only after 5 shots