4070 SS

[desert deuce]

Ahhhhhhhh, obviously I was not clear and failed to explain my recommendations thoroughly. I have tinkered with these old smoke poles quite a bit and assumed too much.

The rifle in question was built in the 19th Century, not subject to SAAMI specifications. Therefore, to begin determining how to load for that rifle one has to know the critical dimensions for that particular rifle and it is probably best to assume that those dimensions are unknown until they are established for that particular chamber and bore.

The simple way to accomplish finding the best way to load for those unknowns is to slug the bore to determine bore and groove diameter and then take a fired, otherwise untouched case, and see if the .410 bullet you have will slide in the mouth of the case easily. If it will not, then the bullet is TOO LARGE in diameter and can precipitate the problems you mentioned as well as stretch your brass and give inconsistent bullet release. You need to use a bullet that slides into the fired case easily even if that is a .403" diameter bullet which in fact it may be. From what you write it is very likely less than .410".

Because, if you have to use a .410" neck expander, or a neck expander at all, to seat the bullet you are implying that .410" diameter bullet is too large for the chamber and that is more important to know than bore/groove at this point because the problem you bring up involves the fired case release in the chamber. The bore mop is of course a good idea ,however, you may be masking the underlying problem, but loading correct ammunition in the first place is far, far more important to good results and optimum accuracy from the rifle.