I've tried them in one rifle I had a few years ago. Custom 1903 Springfield 4 gr. 1-10 twist. The rifle would shoot about 1 1/4" groups at 100 yds with some of my reloads. The accelerators would only group about 4" which wasn't acceptable accuracy for me. Actually the 1 1/4" wasn't really either and I have traded the rifle off. That's the only one I've tried but I sure wasn't impressed.