If you are going to keep magazines loaded in your carry gun or home defense gun, I would suggest rotating magazines every six months in order to keep the magazine springs from loosing strength. Many believe that with modern metallurgy the magazine springs will not develop memory when compressed over long periods of time, however my equipment is expensive and my life is too important to take a chance. I have gotten into the habit of rotating loaded magazines every six months. For me, when we change the clocks in the Spring and Fall seasons, I rotate my magazines. I have the magazines numbered and simply download the magazine(s) that I’ve carried for the last six months and upload the next magazine(s) in sequence.
Numbering your magazines will help you with loaded magazine rotation, and will help you keep up with malfunction trends and determine whether an individual magazine is faulty (example: if the gun malfunctions fairly often with magazine number 4, but fire fine with all the others, it is probably the fault of the magazine). Number your magazines with a Sharpie brand paint pen. These are readily available at Michael’s or any high-end arts & crafts store. I like the oil-based, extra fine point. They come in different colors, but I simply go with white. You can also number your magazines with an electric engraver, however this is permanent. Should you ever want to remove the painted numbers, simply use a dab of mineral spirits on an old rad with a little “elbow grease”. The paint comes right off.
Magazine Color Coding:
Using colored electrical tape is a good way to mark rifle magazines so as to know which magazines are yours after a long day at the range or shooting class. Colored tape is also a good way to mark magazines if you choose to carry more than one type of ammunition type (example: red tape = tracer rounds, green tape = green tip armor piercing rounds, gold tape = frangible rounds, and no tape are plain old FMJ). Obviously using tape in this fashion only works on magazines that extend out of the weapon’s magazine well and only on the part that will be outside of the magazine well.