hepburn 40/2.5

[bruce moulds]

don,
since the original post some research into cerrosafe has revealed that after 200 hours a cast is 0.0025" larger than the actual chamber.
this would bring the case mouth of the chamber to 0.426 minus 0.0025 = 0.4235".
if we call that 0.423, and assume a case wall thickness of 0.010, then a fired case would have 0.003 clearance on a bullet patched to 0.400.
0.423 - (2 x 0.010) = 0.423- 0.020 =0.403"
this chamber has not had a heathen gunsmith pollute it into a greaser dimension.
never thought I would have the luck to see something like this down under.
keep safe,
bruce.