Some use the term clips. I tend to see it used more often by non gun enthusiasts.
Euphemism is a word or expression substituted for one considered to be too harsh or blunt when referring to something unpleasant or embarrassing. Personally I see nothing harsh, blunt, unpleasant or embarrassing about the word magazine. It is just one of the many misused gun terms. There was an article in the July 2014 Guns & Ammo mentioning this and others. From that article.
Clip vs. Magazine
You know that boxy rectangular thingy that holds cartridges and slides into the bottom of your semi-auto pistol? It’s not a clip — no matter how often the term is misused. It’s a magazine.
A magazine holds shells under spring pressure in preparation for feeding into the firearm’s chamber. Examples include box, tubular, drum and rotary magazines. Some are fixed to the firearm while others are removable.
A cartridge “clip” has no spring and does not feed shells directly into the chamber. Rather, clips hold cartridges in the correct sequence for “charging” a specific firearm’s magazine. Stripper clips allow rounds to be “stripped” into the magazine. Other types are fed along with the shells into the magazine — the M1Garand famously operates in this fashion. Once all rounds have been fired, the clip is ejected or otherwise released from the firearm.
In essence, clips feed magazines. Magazines feed firearms.
Another's that makes me smile are:
Assault Rifle.
Some think AR as in AR15 means Assault Rifle. When it actually refers to ArmaLite, after the company that developed it in the late 1950’s.
Cartridge vs. Bullet.
How often do you hear some say they bought a box of bullets instead of cartridges.
There are many others. I was horrible in my English class in school. But whether considered a euphemism, slang, or common term, in my opinion they are not used correctly.
Boy did I digress from our topic, sorry.