E, no doubt the Winchester taper is thin on the muzzle, the FWT, but vs a Rem which tapers quickly to a point then keeps the same dia. the Win. seems to have a little more beef midway in the bbl, but I don't have two in front to compare. Obviously they all work, to varying degrees. I take it very thin tubes are more prone to NOT shoot well if a not so great factory tube, and/or it is a bbl with stress and other 'issues'...true?

Looks like .600 muzzle O.D. is a good minimum in a quality bbl.

Good points, thanks.