All original .270 Weatherby Sauers used a 3/4" long freebore, that was the factory spec. New Weatherbys have a 3/8" throat but you still can't reach the lands with a cartridge that fits the magazine. My Mk-Vs shoot just fine with the long freebore.
The old Sauers had a reputation for good accuracy, although I don't know how many shot sub-moa. What kind of accuracy are you getting with 'normal' .270 bullets? What game will you be shooting? The 180s are designed for heavy game and may or may not expand very much on small deer. I'd do more load testing with 130 and 150-grain bullets. Flat-based bullets often give better accuracy in rifles with long freebore than do bullets with long boattails. FWIW, Weatherby used to load mostly Hornady bullets in their factory loads.
.