I purposely left out the details on the rifle since it would most likely take this off track of my issue of the bullets. I am building it from scratch, my own design. It is made of mild steel and TIG welded together, I have calculated the strength of the design to be safe at 45-70 low pressure loads with a helathy safety factor. That is the reason for the BP/lead loading, to keep pressures low but still be fun.
In doing the design I omitted an actual cartridge in the model so I didn't get to actally "see" if the long cartridge would fit, my bad. The issue of fit is that the hammer is too high in relation to the chamber and does not allow the long 45-70 to fit without hanging up on the top of the hammer. I cannot cut the hammer lower or it will no longer contact the firing pin.
The barrel is chambered in .458WinMag, I can turn down the tenon to fit my reciever and shorten a little and it will basically be a 45-70, I thought I was going to get lucky. I can still cut it down even more and it will accept the 45LC cartidge with the big .458 bullet. I'm trying to do it without a custom reamer which I can do but would rather not. The .458 American is a good idea that I had not thought of but would indeed require a full rechamber and I would prefer a rimmed cartridge that is easier to extract.
As long as the 45LC case didn't rupture the first firing I can size just enough to hold the bullets and leave it at that, basically fire formed. I can modify any dies I need to, or even make some if I have to, that is not a problem but really want to use off the shelf parts.
I don't have any other .45LC guns and don't really plan on any but if that happens I can keep this batch of brass dedicated to this rifle. Since it is a homebuilt (yes it is legal) I cannot ever sell it so it won't be a safety issue for anyone else regarding ammo.
As far as accuracy and velocity goes, since this is a first time design I'll be satisfied if I can hit milk jugs at 50 yds.
So there is the whole story.
Now what do you think about the .458 bullets in the .45LC case? What can I load it with?
And yes, I will pull the trigger with a loooong string the first 10 shots!