First thanks to everyone who contributed to data I found here. What a wealth of info. By far the best I have found on the web.

I put together an upper with a 20" stainless Midway\Stoner barrel (6x45) 1-8 twist. The upper shoots great (1" or less/ w 4x Nikon) providing I use bullets of 75 grains or less. I would have thought with this twist rate I could stabilize at least the 87 or 90 gainers but that has not been the case. The groups for these "heavier" rounds open up to 3 or 4 inches. I wonder if other members using Ar style uppers in 6x45 have had similar results. If you have been successful with heavier bullets in a similar upper what recipe/combination was used? Thanks Bob