A bit of trivia here and i expect im being a bit of a dag,but the revolver she uses seems a bit modern for the period.The one she uses is a 3rd generation Colt Detective Special which was produced from 1973 to 1986.
Politicians are like Nappies. They should both be changed frequently and for the same reason."
One of my "gun buddies" has also informed me that "It is a model 10 .38 special with either a 2" or 2.5" barrel. To be period specific it would need to be one of the first 4 releases of the weapon."
Not saying you're wrong... but there's a chance it's not as anachronistic as it may seem.
I believe it's a Model 19 S&W introduced from 1954 onwards-as it's one prop that has a high profile part on screen in most eps, it's a pity they didn't go with something more accurate for the period. Also, the M1911 Colt automatic featured in the WW1 themed ep shown 13.9.13 was a WW2 made 1911A1 model (introduced in the 1920s onwards)-the one shown had the dull 'parkerised' grey/green finish of WW2 production-also no officer would have a weapon so prominently engraved with their name.
I watched several episodes tonight and saw the gun quite clearly in a few scenes. It is a Smith & Wesson 5-shot snub nose revolver, gold plated, with a 2" barrel. This would be either an I-frame in .38/200 ( British Commonwealth service cartridge) also know as the 'Terrier' or a J-frame in .38 Special ( known as the Chief's Special). The Chief's Special wasnt produced in the early 1920's, so it may be either a Terrier or simply a goof by the props department. After 1957 the j-frame .38 was given the designation 'Model 36'.
The Model 10 looks similar but is larger with a six shot cylinder, and the model 19 is the same but with target sights, chambered in .357 magnum, and wasn't in production until the late 1950's. (the .357 cartridge wasn't invented until 1935.)
Colt revolvers are six-shot and have a different latch on the side, as well as a open ejector rod.
"...Of all the Thompson Gunners, Roland was the best..."
Due to availabilities of firearms down under I assume it's a J-frame .38, perhaps representing an I-frame. It's also not too small in her hands so I would bet $1 that is is Chief's Special.