Welcome to Glocktalk.
Heck of a 1st question.
There are different ways to account for it and I am not sure where to get definitive information.
I think you are asking what is percentage of ammo bought yearly by caliber.
I will give my best guess and some explanation.
40% 9mm. It is cheaper so I think more rounds get shot and it has been around a long time. Lots of guns out there for it. Generally 9mm magazines hold more rounds so if you go the range and shot 10 magazines worth of 9 you probably shoot more rounds then if you shoot 10 magazines of .45. 9mm is popular in action shooting and those guys burn through some ammo more then your average plinker. Also in pistol caliber carbines and sub guns 9mm is popular so more options to shoot it. The cost of buying it vs. reloading it is (or was) close enough I know people who buy 9mm but load their own .40 and .45.
15% .40. Not been around as long. It may be popular with police departments but in general police officers don't shoot a lot. Officer does not equal gun enthusiast does not mean they can't be but I bet 80% shoot less then 150 rounds a year. In action shooting competitions I know a lot of shooters don't bother with .40 despite having many handguns. They use 9mm for the minor scoring and use .45 for major.
25% .45. More expensive so get used less. Popular in bulls eye shooting but the volume of rounds fired is pretty low compared to action shooting.
10% .38 Special. Lots of guns shoot it but you shoot it slower. At matches you will have a few revolver guys and 70 non revolver shooters.
1% .38 Super. I think much more is used but it is almost exclusively reloaded by the shooter for competition.
9% The rest. (.45 Colt, 10MM, .357 Sig, .44, Cowboy Loads, etc.)
We had a bad year or so but it looks like everything is back available best I can tell. .380 still seems a little hit or miss but going to local retailer you will probably have good luck sticking to 9mm, .40, or .45. It is hard to account for the guy who came just before you and bought 20 boxes. If you are getting your first handgun and want a Glock I would recommend starting with a G17 or G19 based on what fits best in your hand then go from there. It uses the least expensive ammo so you can buy more rounds and shoot them and it will be the mildest round to start out with.
Good luck and let us know what you end up with.
Last edited by Jon_R; 11-07-2010 at 18:31..