I have a theory and it is just that a theory. I suspect that the reason the QLA messes with the conical accuracy is that when the conical reaches the QLA portion of the barrel the gas pushing it can escape around the base of the conical and cause a disturbance that starts to make the bullet unstable. The reason it does not do this with a sabot load is that the sabot expands enough and the petals are opening just slightly and the combination stops the gas from escaping around the bullet/sabot load. Personally I find it hard to believe that T/C cannot machine a QLA concentric with the bore (although apparently some have measured them and claim that they are not machined correctly). I have not shot any conicals in my Omega other than Powerbelts and they shoot quite well: however, the powerbelt also has a plastic seal at the rear which would stop the gas excaping around the bullet just like a sabot if that is what is really causing the problems with solid lead conicals. Some have had decent luck with conicals if they use a felt wad below the bullet and again this "seal" may be the answer to rifles with QLA.