my son has done a few octagon barrels out of a bc and ruger round barrels, also flutes..
and he states " for use with trapdoor loads only"
mostly because the owners only do TD loads for there type of pleasure shoot'n...
and his liability purposes.
big mill ? how bout a 6ft bridgeport.... i think thats what we installed in his shop
20 years ago. i can't remember !!!
when he comes back from TDY, i'll ask him.