Hey, I was looking at my 45-70 loads i Have been working on. I notice the 300gr partition I am loading that there were bigger gaps on one side than the other of the cannelure. Either the brass is not square of the bullet is not straight loading. I am rotating the brass/bullet 3 times while seating also as regular.

I took out the stem/seater plug and its made for a RN. Wonder if this makes a difference? Called RCBS, they think it is the problem and are sending me a cowboy 45-70 seater plug which they said is made for more flatnoses not roundnoses.

What does others see? Wonder if I should flair more or get an M die?

I had the same problem with the 300gr NP, even using the M-die for it and Cast Performance bullets. Solved the issue by using a Lee Loader just to center the bullet and get it started in the case, then seat as usual in the press. It lines em up dead center straight with no trouble. The customary bulge in the case at the bullet base is even all the way around, not heavy on one side. That's the only time I use the Lee Loader anymore, but it works well.

What do you mean by lee loader? you mean lee seater?

The Lee Loader....


Lee Loader

http://www.leeprecision.com/cgi/catalog/browse.cgi?1132...alog/cleeloader.html

Sells for about $13-$20 new, less on Ebay.