Well I just received a new Shilen Ratchet 4 groove,.812 no taper. I hope I didn't make a big mistake on the .812 no taper. This is going on my 40X #2. It has a Benchmark 2 groove rev. tapper 16.5 twist. Sometimes this would shoot like a house afire and the next target would be a total disaster.It seemed to be really inconsistent.I shrugged it off as just shooter error.Late in the summer I went back to 40X #1 and stated shooting consistently better. So this summer we will try another shilen and hopefully a lot more consistent. I think the cold and radical changes in DA up here are a lot of the problems with the 2 groove. Then again The old shooter error comes in.