1. That must mean something to some people, but it doesn’t mean anything to me. FWIW, I’m an immigrant, with zero military experience (other than reading some books). That may or may not explain my bafflement.

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   1. rounds in a standard mag for an AR platform

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   2. @pkoning: As Bob noted below, it’s about the number of rounds loaded in a 30 round AR magazine.

      As soon as I saw his post, I remembered it.

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   3. In the US military our primary arms was an AR15 platform rifle. In the OLD days(1960s-1970s) the magazines were sometimes not very good. It was taught to put 27-28 rounds in a 30 round mag to take some pressure off the magizine feed lips. Not really nessasary today with modern mags.. hope this helps

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2. Pardon my ignorance, but, if the mag capacity is 30 rounds, why would you load only 28? In a defensive shoot situation, you may be held responsible for rounds you didn’t fire if you load below capacity. Why would you take that risk?

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   1. In addition to what Curby mentioned above, some magazines are harder to seat with a closed bolt if loaded to full capacity.

      If a magazine is full, especially in older magazines, the spring is at or near full compression and the top round can’t move further down much if any distance. (Thats what “at capacity” means, right? You can’t push the top round down enough to squeeze in another round.)

      Now, in an AR, the top round in the magazine is pushed down a little by the bottom of the closed bolt when the mag is properly seated and the bolt is closed. This is normal, and is true no matter how many rounds are in the magazine.

      So think about how the rounds and magazine body behave when you insert a magazine against a closed bolt. When the top round hits the bottom of the bolt, it stops moving; but the magazine body has to slide up a little further to fully engage with the bolt catch.

      So if you try to seat a full mag against a closed bolt, the top round might not be able to go deep enough into the magazine to let the mag body fully engage with the mag catch. In that case, the mag might drop out on you, or otherwise cause a jam because it’s too low wrt the bolt, when the action cycles.

      The most common scenario for this, I’d think, would be if you choose to swap out a mag that you know is getting low on ammo, with a new one.

      Newer magazines, such as Magpuls, are generally engineered to not have this issue.

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3. insert comment and hand wavery about spring compression and feed lips fatigue and failure to feed. Mags are consumable, treat them as such, for now. Don’t get rid of them but remove problematic ones from circulation.

   1. … or better yet, have them marked for practise range only, so that you can get some real life malfunction drills under the belt.

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      1. Great idea!

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