On the Colt Single Action Army what is

I was looking hard at .32-20 but since my .44-40 carbine came in I have been lured by the old charm of cartridge commonality. And the .44 would afford some greater use past just fun shooting.

it was a Great Western, so hard to tell at a glance. Those look like Great Western grips for sure. The hammer is the big tell but with it down...

I sure thought I remembered it distinctly nickel from the show, different than everyone else's. Plus it was a big 7-1/2".

Where is Newly when you need him?! There is so much speculation and misinformation it's hard to tell for sure.

One source:
"The production company rented several Colt revolvers for Arness during his 20-year run, and this particular one was noted in the Stembridge records as being rented to the show in 1961.

Gunsmoke and firearms aficionados may also remember Dillon using a Great Western revolver. That was true, in the early part of the series. After contacting Colt and finding out the company had no plans to resurrect the single action Army, Bill Wilson and partners formed the Great Western Arms Company in 1954 and reproduced an almost-exact clone to be used in Western movies and TV shows, including Gunsmoke. Two years after the Great Western was introduced, Colt brought back the single action Army, and the company, unable to beat the real deal, finally folded in 1962. Even so, John Wayne brought Great Western back to the big screen, when he used the single action Army as his main handgun in 1976’s The Shootist. His saddle from that film sold at High Noon as well."