If I want Find a Load for a 325 grn FTX Hornady bullet for a
45-70 at 1500 fps ,How do I find a Type/Amount of Powder for it?
Siera says to use IMR 4198 with a 300 HP , 42.0 grns powder
To Equel what I am looking for . ( I Just got off the phone with them)
For a 14" G2 w/Muzzle Brake
I have Yet to try Reloading but have Bought Press Kit , Dies
So Far.
I am Looking to Asimilate 454 casull in a Contender

I would give Hornady a call and I'm sure they can get you started. Western(Ramshot) powders has a program that they use that can give you a starting and max load for their powders.

You could also try Hodgdon power companies website. The have a reloading data section

Their load charts are also online...i'll go look them up and update this post shortly.

http://www.ramshot.com/powders/loadguide/Ramshot%20Load%20Guide%20V4.3b.pdf

This is a 15 page PDF file. The 45-70 is in the Rifle section and for a 24" barrel, but you could figure it out close enough to get some starting loads.

Usually one will use the Trapdoor level loads for Contenders.

The Thompson Center Contender loading manual is a great place to start. Here is a link to one for sale;

The complete load manual for the Thompson/Center Contender

They usually list laod tables from most of the powder and bullet companies for each cartridge. It's like having 5 or 6 loading manuals combined into one. It's money well spent.

That One I already have.
It seams to be a Vary Good Manual