So after a lot time spent shooting and casting I found a match thanks to the folks at accurate molds.
The 45-250-P checked all of the right boxes for me.
It seals the chambers on my 1873 with no blow back.
Shoots point of aim in my old ruger vaquero fixed sight 45's.
Has a short enough nose to function and feed through my 1873 toggle link.
The nose is also tapered enough to cycle through my 1892 which doesnt sound like a big deal but several boolits just didn't work in my 1892.
Lastly it shoots accuratly in all of my guns and packs enough weight to hunt with this fall.
I bought a 4 cavity mold with one cavity gas checked for plus P loads out of the rugers and marlins!
A big thank you to the folks at accurate molds.