This is for information only,
Every AR member already knows this; the 45-70 Government chamber does not have any throat; all ammo, since 1873 is made such that none is needed. The Ruger #1 follows suit; their chamber does have a chamfer in front of the chamber, but no real "leade", or throat. And I have loaded many hundreds of them with all manner of bullets, seated to the crimp groove with no issues noted. All commercial jacketed bullets that I know of, accommodate this. Here are three examples; a 300 grain Hornady, a 350 grain Speer, and a 405 Remington. All load and fire in a Ruger #1 easily.

Thanks for posting this Tom, I did not know. That 350gr Speer looks more pointy than the 350gr Hornady flat point that I can’t get to fit. I will go back and double check, but good to see the 300gr Hornady works.

Yes and the 350 Speer is a tough bullet; I killed a bear with one once. rbjt
I don't have any 350 Hornadys to check. But Ruger used two different reamers and some do have longer throats. In order to use the Hornady, you will need to ream a longer throat in the chamber, which I can do.

Or ream out a .45-90 chamber and have .3 inch room for more powder!
Both my 1886 .45-90 and my new custom Beretta
.45-90 double hold enough powder to shoot 450 grain NF solids at 2150 fps.

You know the 1886 look, so I just posted the DR with 26 inch barrels, same length as the 1886.

I can do that too. If the owner wants that. My 45 2.4 inch reamer, has a throat.