Originally Posted by
Bad *** Wallace
I've been working with Cadets and the 310 / 32-20 conversions for many years. An old time gunsmith who used to convert them told me that the conversion involved using a 310 reamer and cutting the chamber to the depth of the 32/20, then cutting the thicker rim to suit! When fireformed you have a case that is the length of 32/20 but the diameter of the 310 Cadet which was nominally designed to take a .316 boolit. Early barrels and early ammunition (1910-12) had bores of .316. Indeed we had a manufacturer in Australia for many years of jacketed boolits that were .316 x 120gn.
A batch of replacement barrels came into the country which were oversized running .319-.321 and in 1930 the Colonial Arms Co. in South Australia came up with the idea of a heeled boolit to get these replacements to shoot with some sort of accuracy. This does not mean to say that all Cadets require a heeled boolit.
I have 11 original rifles and 10 used a conventional plain base non-heeled boolit which is cast and sized to .317". Only one (a Greener) has a bore of .321"
My main concern with the idea of a .312" hollow based expanding boolit is that you have to overwork the brass to even get it to hold a projectile after the case has been fireformed in the converted rifle!