"Cowboy" low-power 454 Casull/ 45 "Extra Long" Colt loads for R92?

[Begle1]

I've been working on getting a 454 Rossi R92 to feed 45 Colt reliably and it certainly seems (non-surprisingly I guess) that longer cartridges work better.

Max 45 Colt length spec is 1.600". Max 454 Casull length spec is 1.77". I can get 10 into the magazine as long as they're around 1.75". So I'd like to load some Cowboy-powered loads to a COAL of around 1.75".

I made some 1.75" dummy rounds with 45 Colt brass and they did seem to feed pretty good, but I was having problems getting my 250 grain bullets to stay seated with so much of the bullet sticking out of the case.

So I had the thought to use Casull brass, but at that point I'd be using an even more cavernous chamber, and also a small rifle primer, so it'd leave me in a total desert as far as published load data goes. (As far as I know.)



Does anybody have any insight on a jumping off point for a Casull Cowboy load?

I've been loading 1.6" 45 Colt with a 250 grain bullet over 6.0 grains of Green Dot, which gives me a consistent 1000 fps out of the 20" R92 barrel. I'd like to stay around that level or a bit slower, but with a Casull case at 1.75". And I'd love to use my same 250 grain bullets.

Or I guess another approach would be to use a longer (and heavier) than usual bullet in a 45 Colt case?

(I'm quite inexperienced at all of this so apologies if I'm not making any sense at all.)