Bote,

I've been playing with trapdoor loads for about a year now. Two things I've figured out:

1. A flat based 405 grain bullet does not seem to work well in these rifles. You need a cupped base 405 or flat based 500 grain in a 20-1 alloy. Both these can be purchased, pre-lubed in SPG BP lube, from Buffalo Arms. These are what you want.

2. The 45-70 round was one of THE most tested rounds prior to introduction into the services. There is a book called "Loading Cartridges for the Original 45-70 Springfield Rifle and Carbine" that provides a lot of info on how to replicate the original load and pointers that will make your rifle pretty accurate. I would get this book and read it, it helped me a lot.

Bottom line, for me anyway, I couldn't hit the broad side of a barn with the cheap 405 gr hard cast Bullets and smokeless powder. I read this book using the suggested techniques and now shoot 2-3 in groups with 65 grs of FFg BP, .060 fiber was and the flat based 500 gr bullet from Buffalo Arms with a heavy crimp.

Stretch