I am loading for a 7mm using Lee Dies and was surprised to see a big difference in accuracy by adding a Lee Factory crimp die. I am loading hunting rounds so crimping is necessary. The bullet seater die does not crimp at all. Both targets are 5 rounds single load at 100 yards with, new WW Super brass, 139 gr Hornady SST,62.2 gr of RL 19, C.O.L. 3.36, shot out of a browning A bolt Medallion with a boss set to 2.5. Hornady Manual says 3000 fps for this load. I do not have a crono yet so I could not check. The tight group is with the crimp loose group without. I did load 4 other loads in .5 grain intervals to 63.3 gr with crimp none shot as well as 62.2 gr load. I could probably tune the boss to the other rounds but do not see any reason to with the max gain of 100 fps +-. any thoughts?