You are quite welcome. I'm the Village Idiot compared to some folks on this and other forums. I got started collecting firearms a few years back and have done a lot of research. That attention to detail thing or an OCD drives me nuts sometimes.
How the handgun evolved from the early days when it was black powder being stuffed down the barrel of a single shot pistol, then into cylinders (Sam Colt) followed by cartridges (Elias White/Smith &Wesson) caught my attention. Along come semi-automatics in the early 1900s and both them and revolvers evolved accordingly. I've bought more than a few of them in the process. But it's more "fun" than stamps. Here are the two oldest gals in my collection.
Above is a Colt Model 1849 Pocket Pistol, made in 1860, which later evolved into the Colt Police Positive Revolver. Loads of changes along the way. So comparing one gun to another is like matching Chevy's, Fords, VWs and BMWs, designed and built to suit different tastes.
Here's a S&W Model 1 2nd Issue it was a flip top, which was followed by Break Tops and the Swing Out Cylinders. During the Civil War soldiers went off to war with a S&W 22 or 32 Caliber revolver stuffed in their pocket as a Back Up Gun. The US Army even bought a few for Artillery Troops to carry in lieu of rifles. This one was made in 1865.
Anyway I'm getting into a rant here but if you want to get into a little history or take a real close look at firearms have at it. There's load of stuff out there.