(@Brad) Using @Rocketpak’s link, it looks like they took the mold of the Ruger Mark #… maybe a 3? The 22/45 doesn’t have as steep of an angle on the grip (I have an older 22/45). The beginning of barrel looks like the Mark III Competition model, but the sights look like the standard model. Just to show how hilarious Hollywood’s info is on firearms, RocketPak’s link states it “is generally based on the design of the 45 caliber pistol.”
Hopefully the pics show up (Ruger Mark III Competition and Mark III standard from web):
A newer Ruger 22/45 for comparison. Notice the grip angle and contol placement:
Another side note… I’ve always thought the Ruger Mark # 22’s were modeled after the Luger… again, following the Hollywood article, it’s funny, since they were in 9mm (except for like three .45 ACP prototypes/proof of concepts that were made to sell to the American army pre WWII, and the newer “Lugerman” 45 which I don’t think was available at the date of the ST episode).