If you go by the amount of ammunition made each year it is the .22 Long Rifle.
Handgun
Considering that the British Commonwealth had the most men on the ground (this would include Australians, New Zealanders and Canadians) the most common gun was probably the Lee Enfield infantry rifle. On the opposing side the most common gun would have been Mauser rifles.
M16 series
hand gun is the most common
The most common hand-gun caliber used to be 9mm Luger. Recently I bought a pistol and took a self-defense course. Now it seems the most popular caliber is the.40 Caliber Smith and Wesson.********There are popular, and there are most common. The most common gun caliber is .22 rimfire, in terms of the total number sold.
The most common hand gun used in James Bond is, The Walther PPK.
The most common usage for a screw gun is to replace a screwdriver. The screw gun is a very convenient tool that makes projects with a lot of screws faster to complete.
.69 caliber Springfield
No specific records
the sten?
Barrel and receiver are the most common place.
air and gun powder are the most common.