Mike,
Unfortunately, a lot of magazines don't work quite right. Most of them are not fixable besides cleaning inside and out. Your question is sufficiently broad that you have gotten a lot of answers, many of which are just arguing. I'll try once more to explain a rational system regarding magazines.
Duty Magazines:
-With duty magazines, the goal is to always have a supply of known tested work for sure duty magazines.
-A CCW or police carried pistol should have two or even three full sets of magazines that have been tested through use, never used for any thing other than duty or CCW, and protected from damage.
-You always know those magazines will work.
-You know that because the last time you used them, they worked and since then you have not let anything happen to them.
-Likewise, the ammunition in those magazines should be fresh, clean, and kept that way.
-You do not constantly load and unload the ammo in those magazines. Just doing that degrades the dependability of the ammo by nicking the rims and sides of the cases.
-How often to replace the top two or three rounds in a magazine where they are chambered, extracted, reloaded, and rechambered when a gun has to be cleared is a whole nother long question.
-More than a couple times should mean the top rounds get junked and replaced.
-Neither the magazines nor the ammo in them are an expendable, throwaway, droppable, stomppable item.
-You protect those knowing they are all that stands between you and harm.
-There is never even a question of dropping them on the ground. You don't use them for anything other than carrying on duty or CCW.
-When you rotate duty or CCW magazine sets, rotate the ammo in them.
Training Magazines:
-Training magazines are just that.
-Other sets of magazines for shooting at practice, qualification, or training sessions.
-With these, you push the button and drop them on the ground without a single thought.
-They either get damaged or not, but so what. Do with them anything your training theories dictate that you would do in the real world if reloading while someone was shooting at you.
-Practice the same as you would in theory do for real.
-That is usually, push the button and reload a new one and move on.
-These magazines are marked or identified differently than the duty magazines.
-Train for real, trash the mags, worry not.
Competition Magazines:
-Note that duty guns don't too often get used for competion. Some do of course.
-Competition guns and their accessories including magazines are a subset of equipment.
-I personally would never mix competition magazines with any CCW or duty gear. Period.
-If you can play the game, buy the gear to keep it separate.
The end result of this set of ideas is that your duty or CCW gun always has known to work for sure magzines with ammo that you have not wrecked by loading and unloading 10 times in the last 2 months.