People say that you should load AR mags with 28 rounds rather than 30 to prevent jams. I read somewhere that the problem is that people (soldiers) would take the mags apart and put them back together in such a way that the springs didnt compress properly and when thirty mags did wind up getting stuffed into the mag there would be problems. So….logically, the answer was to play it safe and always go with 28 rounds rather than learn to re-assemble the mag correctly, I suppose. To each their own, I suppose.
Since the AR is so ubiquitous there is no shortage of manufacturers of magazines out there. “Contract mags” are what most of us wind up with. Simply put, these are magazines that are built under contract for Uncle Sam.
Theres three kinds of AR mags out there these days – plastic, aluminum and steel. Speaking from my own experience, I almost always go with the original aluminum mags. I’ve met very few plastic mags that were reliable, fit well, and could take abuse. Some folks love the Pmag from Magpul but I’ve read mixed things about them. The big drawbacks to plastic magazines as Ive experienced them have been durability and fit. I try to take good care of my mags and not drop them onto hard surfaces, etc, but when the zombies get here it’ll be nice to know that I can drop mags on the sidewalk at a dead run and not have them chip or break…I just havent met a plastic magazine yet that makes me feel comfortable in that regard. The other problem Ive had with plastic mags, and this was a problem on early first-gen Glock mags too, is that when the mag is fully loaded it swells a bit and makes insertion/removal from the magazine well a bit tricky. If it doesnt drop free from the AR when I push the mag release, I dont want it. The Pmags get great reviews but they also have their detractors. I have a couple of them and they seem to work okay, although I havent tested them to destruction yet. On the other hand, I have AR mags from waaaaaaay back that still work just fine.
The steel mags, which I understand are mostly surplus British SA80 mags although there are some commercial ones as well, seem to work but I’m squeamish about constantly inserting/removing a steel magazine into/from an aluminum magazine well…it seems like a recipe for wear. I do have a few steel mags that Ive kept over the years but I almost never use them and they are relegated to tertiary-level spares. Given the low price of aluminum mags these days I may just strip them for springs and followers and toss them.
That leaves aluminum mags. Although the mags have pretty much stayed the same over the years, the innards have not. The biggest change has been in followers. I have original Colt mags with the alloy followers (thats old, baby!) Followers then changed from black plastic to green and now to tan. The latest feature is the ‘anti-tilt’ follower which seems to be becoming standard with almost everyones AR mags these days. While there are plenty of makers of AR mags out there, I’ve been stocking up on the ones from CProducts. Quality has been very good and they are priced extremely well. Often you can find wholesalers dumping them for less than $10 ea. in quantity.
For drum magazines, theres really only two options – the 90-round drum which is pretty darn big and bulky, and the 100-round Beta magazine. I’ve very little experience with either one but the Beta seems like a better choice just in terms of size and carryability.
Were someone to ask me what they should buy and stick away for that Rainy Day, I’d say get as many of the CProduct or genuine GI mags as possible. I prefer 30-rd mags although a couple 20′s are handy for carrying in your pocket. I’d stay away from anything aftermarket like the dreded USA-branded mags, any steel mags, and most plastic mags. There are some 40- and even 50-round mags out there but I question their reliability and wouldnt advise getting them unless youre going to test them thoroughly.
Our buddy ,Rawles has a FAQ about AR mags thats worth reading here.