Crazy difference in primers.
Hey guys first time poster here. I just got back from shooting with a buddy of mine we both shot 300 RUMs . his is a new rem 700 mostly stock and mine is about 6 years old and i have action,piller bedded it, new mag box, free floated. I do the reloading for us and late last year i went from rem primers 9 1/2 to the CCIs everything else was the same we shot the Berger 210 VLDs and 93gn of H-1000. After hunting Colorado last year where we did a lot of shooting both of us had buck and doe tags. all of my shells had the CCI primers and half of my buddys had CCIs and the other half were the Rem 9 1/2s. We wanted to check our 200yd zeros after running our turrets up and down so many times wile hunting. Mike shoots a Burris signiture s and i a Leopold, I know my Leopold tracks real consistant but mike hadnt had the Burris on long enough to know if he could trust it. So we started shooting off of a portable bench with one of those gun vises that uses the plunger to fire the gun hands free. All straped up to the bench. First 4-5 shots were all alround the bulls eye about a 1" group with the rem primers the 6th shot with the CCI primer load it hit 10" left. We looked at each other like what the heck was that. so we sent another down range , also 10" left and another same 10" left so we sent one of the rem 9 1/2s in there hits bull eye. We went back and forth about 5 times and had 2 real nice groups but they were 9-10" apart. So i put my gun on the vice and shot it 10 times with the same out come. The only other difference was that the CCIs were set back .050 shorter than the shells loaded with the Rem primers.
Has anyone else had this happen? I have found that the CCis are a little bit hotter they seem to add about 15-20 fps over the Rems but i wouldnt think that that would kick them left 10" at 200yards Not real a delema we have decided to just buy a brick of the CCis and set all OAL to the same . Reason for the longer shells was that they were loaded for his OAL but they wouldnt fit in his Wyatts box for hunting. I just wouldnt have thought that the primer or the length would have anythin to do with left and right?????
Sorry for the long post but i thought i would start off with a bang Thanks, Mike