The word "clip" was briefly mentioned in this article. I never understood the "don't call 'magazines' 'clips'" fanaticism among gun enthusiasts. It seems to be a pretty common colloquialism for "magazine" in popular culture now.
It's because "clip" refers to somthing different, if related. A clip refers specifically to a mechanism that clips onto multiple rounds of ammo in order to allow it to be inserted into a (fixed) magazine[0]. Some guns with fixed magazines use clips to enable faster reloading, while guns with removable magazines don't need a clip, because the entire magazine is swapped out.
From outward appearances, and to a possibly untrained observer, reloading via inserting a clip looks similar to reloading with a removable magazine, which I presume is the source of the conflation. But, for some people, correct terminology is important; "coder" vs "hacker" vs "cracker", I suppose?
Its a way to distinguish those who know what they are talking about from those who do not. See also shibboleth [1]
You see it all the time in other communities, like how people here on HN would laugh at someone purporting to be a 'hacker' going on about how they like to 'program in HTML'.
Now, if you really want to have fun with gun people, break out the old suppressor vs. silencer argument. The distinction between the two is ill-defined and there may or may not be a difference depending on who you ask, but some people will argue for hours over it.
But honestly, I think it has more to do with ham-fisted and ignorant attempts by lawmakers to ban guns. The amount of technical illiteracy that litters gun laws is frustrating in the extreme to people who have to actually comply with those laws. Clip/magazine snobbery is just a way of venting that frustration.
Almost no modern weapons use clips; the last popular one was the M1 Garand (standard issue US infantry rifle in WW2).
It's a more than a semantic difference because there are some weapons that are capable of accepting both magazines and clips. Though such weapons are rare and I can't think of a modern example, there is a good reason for being picky.
Some samples that come to mind:
http://en.wikipedia.org/wiki/Mannlicher_M1895
http://en.wikipedia.org/wiki/Mauser_C96 (the old "broom-handle" mauser)
I'm sure there's a few others. I saw a couple on Forgotten Weapons (they have a really great Youtube channel--check it out sometime) besides these two, but their names escape me.
That does not make that terminology incorrect.
My pet theory is that the M1 is a big source of the current conflation of "clip" and "magazine". Millions of men were conscripted for WW2 and Korea in the US and for a great many of them their first experience with a self-loading firearm was with the M1 they were issued in training. To many of them, no matter how many autoloaders they were exposed to aftward, that thing you shoved into the gun that held the cartridges was called a CLIP, because that's what the drill sergeant in training called it. These men then went on to spread this habit of using CLIP and MAGAZINE interchangeably, and at this point it is too ingrained in the vernacular to ever go away.
Huh, never thought about that. I'd imagine one way to test this theory might be to examine changes in the colloquial use of both terms relative to specific firearms and proximity to WWII.
Although, as I pointed out in another comment, some firearms used both: An internal clip-fed magazine. Bet that's an even better source for confusion. :)