Re: Site Needs .243/.243AI Loads & Comments 243 AI, minimum spec chamber, zero freebore, .269 neck. Barrel is a 28" Hart that is a 1-12 twist. We shot a couple dozen of these in a MHV contour with a muzzle break on dog towns. We shot fireforming loads in Rem 7/08 brass of 47g of Win 760 with cci250 primers with a 70g Nosler ballistic tip or 70g TNT at 3750 fps, formed loads as48.0-48.5g of Win 760 at 3850 fps. Accuracy was less than .285 for three shot groups. If you stick a mag primer and up your powder charge to 49.5g, you are over the 4000 f[s with the 70's. 760 is easy on barrels. In a 243 in 700sporters, two loads sing out to the land!!! 47.0g of H4350 with a win primer in a 70g Nosler 44.5g of Win 760 with a fed 210 primer with a 70 is extremely accurate.