Blue Book of Gun Values
this is a called a triger action, shot gun.
When someone refers to the "Gun that won the West", they are usually referring to Colt's Single Action .44 caliber Army Model Revolver, also called "The Peacemaker".
as source on the internet called gun digest books for cowboy action shooting which came up when i typed in squire bingham 22 caliber revolver said it was as follows: E 225 VG 125 G 100 F 80 P 60 I have one in just the 22 caliber.
The Colt Single Action Army revolver. AKA the Colt .45
IF you are referring to firing in the single action mode, the phrase "pulling back the hammer" is used.
The standard caliber is .45 acp. That is a short fat pistol caliber that fires a 230 grain bullet at about 800 feet per second velocity. Lighter bullets down to about 185 grains are available, and they travel faster, possibly as high as 1100 f.p.s. The model 1911 pistol is a semi-automatic, not to be confused with an equally famous revolver made by Colt, often chambered in what is also called .45 caliber, but that model 1873 revolver would use the .45 Colt or .45 Long Colt cartridge, which is a rimmed revolver round, much longer in size that the .45 acp, and firing a heaver bullet at similar velocity.
He used two types handguns. One is a 1873 Colt single-action Army revolver, commonly referred to as "Single Action Army" or SSA. The other is a .45 Caliber Modified Kimber Gold Combat II semi-automatic pistol. He carried two of the Kimber guns.
50 caliber
there's no such thing as a 6868 caliber
Caliber is American, MM is Metric. One type of munitions can be called two different sizes.
There is also a gun called a Black Power Revolver.
It was introduced in 1934. There is a website called Winchester Collector that might be helpful.