Here are a few more photos for some size comparison.
At the top of this photo is a Colt New Service chambered for 45 Colt. It has the same basic frame as the later Model 1917 Colt except for the shape of the frame around the trigger guard. Below the New Service is a Smith and Wesson N frame 45 ACP Model 1917. The Smith is a big gun but it is dwarfed by the New Service. It is the biggest revolver I own.
Here is the same New Service and a Single Action Army, both chambered for 45 Colt. The New Service dwarfs the SAA too.
At this point I have two New Service revolvers. The 45 Colt is at the top, the 44-40 is at the bottom.
This photo will help give some scale to the other revolvers I posted a while ago.
At the top is the Army Special from 1921. This revolver is basically the same as a Colt Official Police just an older name. It is chambered for 38 Special. It is a little bigger than a K frame S&W.
Next down is the Colt Police Positive Special from 1922, also chambered for 38 Special. The frame of this revolver is the same frame that was later used for the Colt Detective Special.
At the lower left is a Colt Pocket Positive chambered for 32 Long Colt. Not the same as 32 S&W Long or 32 Colt New Police. The 32 Long Colt cartridge is an obsolete cartridge with a heeled bullet. The other cartridges will not fit, they are slightly too big. This little revolver was made in 1908.
Last at the lower right is a 32 Pocket Positive chambered for 32 Colt New Police or 32 S&W Long. It was made in 1917.