I tested it one a several loads in several rifles. Not many, but of those tested uncrimped shot better. To be fair all bullets had a crimping groove, and all were seated to put the groove at the case mouth. Lee's response sounds good to me, but I haven't been able to get better accuracy with crimping. One test was with the .30-30. Uncrimped shot best, Lee factory crimp second, and Lee roll crimp worst. One test, I don't remember which one, the crimped loads were much worse, but usually the difference was small. All testing was done with 10 shot groups at 100 yards.
