40 70 PP problem

[ken s]

Ok, Well sounds like your trying to use that bullet as a groove diameter.
The .403" bore diameter it sounds like you might have a Remington. I have no idea what your groove diameter is, but with the .403 bore diameter and a .417? diameter bullet you will have a hard time loading the round unless the ogive is seated off the lead.
I take it that the Buff arms cases are the stretched .30-40 brass. If so the wall thickness is .010" +- some maybe. So you will need a chamber dimension at the case neck at least .437" to load that round with out to much thumb pressure and a clean throat between shots.
Ken all of this is a guess with out knowing what exactly you have for a chamber.
But I would suggest you get some paper that is two thousands or less in thickness and give this a try.
You can find some thinner paper at Walmart in the craft section or ask. at a paper store. Take a micrometer with you when you look for paper. With your .403 bore .0023" thick would be just fine for shooting the bullets closer to bore. I like mine patched one thousand over bore for my rifles. But if you want to go for groove diameter patched bullets then adjust your paper close to your groove diameter and seat your bullet depth accordingly for your chamber. It's not a good idea to go to much over groove diameter. I wouldn't go more then one thousands over groove if this is your intend.
Then work up a ladder load from zero to top compression you feel you need in one grain intervals 3 shots each. Usually 21 rounds fired will give you an idea what to tune up a little more.

Kurt

Kurt