I have seen that happen many times. I have seen tight 100 yard groups fall apart at 150. When I was doing the load development for my 460 gr paper patch bullets I was getting 2" groups at 100 yards. I went to 150 and I didn't even hit paper. I moved my load down from 90 to 80 grains and I was back on track. I shot a couple groups at 200 that were sub 5" and I stayed with that load. Ron