I have an interesting and infururating phenomenon going on with my AR 10. More correctly it’s a DPMS style large frame AR. I have a JP upper and a DPMS lower. Anyway, I bought a Dracos barrel in 260 Rem to replace my JP 260 barrel. I had nothing but problems getting it to group. More specifically it would shoot the first shot high and group the next X number of shoots very nicely about 1 inch below. It shot very well except for that first shot. So well in fact that I went to great lengths to figure it out. The interesting thing is that it only happened when the barrel was cold. If I kept the barrel warm by shooting another group within a minute or two they all grouped very well. If I waited 5 min or so, then I was back to 1 high and the rest 1 inch lower. This was repeatable through powder charge increases when shooting a ladder test. This was with 130 ELDs and H4350. I also shot 123 ELDs and got the same result except closer to 2 inches between the first and the rest of the shots. Talked to Dracos many times and tried many things, they all yielded the same results. So Dracos sends me a new 260 barrel. Same thing. I even think that maybe my JP receiver is warped so I build a whole new rifle out of Aero parts and get the same result. I also tried unsupressed, but all it changed was the orientation of the first bullet to the rest. Finally Dracos takes back my second 260Rem barrel and sends me 6.5 Creedmoor. Same result. I’m handloading mostly, but have tried factory ammo with the same result. Been working on this for over a year. I keep my hair cut short or I would have pulled it all out by now. Any thoughts on this?