So I've started loading .44-40 with the once-fired magtech brass, bullets from a Lee 429-200-RF 6 cavity mould and using a set of RCBS cowboy .44-40 dies.
I found that once the brass has been run through the dies the outside neck diameter is almost identical to the bullet diameter (.429/.430) so it requires an extremely heavy flare to get the bullet started and once seated it expands the case to the point where the rounds won't chamber. I have used the crimp built into the bullet seating die but even with the maximum crimp it still won't chamber. I've tried them in a few rifles so it's not a problem with the rifles. I measured the neck of some factory rounds and they are about .440 whilst mine are .445 but given the bullets come out exactly .429 I'm not sure where I've gone wrong. Does anyone have any advice?
I have included some pictures comparing my rounds to a factory one from magtech.
My round on the left, magtech factory on the right
Factory round and empty case chambering fine
My round not chambering