I have two mid-1980s vintage Winchester/USRA 70 FWTs, from the European export run of push-feed rifles, that are throated for 156/160 grain RN bullets, so shorter/lighter bullets have a fair jump of free-bore to the rifling. These rifles have never shot particularly good groups with bullets lighter/shorter than the 129 grain Hornadys. If you want a faster 6.5x55, the easiest path is via a 6.5-284 finish reamer and its added 9 grains of case capacity, 57 to 66.
