Download 20-Round AR-15 Mags?

[Badger Arms]

Okay, I've yet to fire a fully loaded 20-round magazine. My question to people who download them is... why? Is there an issue with the spring pressure? Was there an issue with the follower? What was and/or is the cause of this.

I've also heard that you don't need to download your 30 rounders, however I still hear that people do. Is there any reason to do this? I'm perplexed by this. I've loaded my 30 rounders with 30 rounds, every time and I don't have any problems. The 20 rounders are only used for competition and load development. Those instances call for 2 and 8 rounds as well as a single-load device for slow-fire and chronographing.

 

[jobu07]

I have never had a problem loading any of my 20's or 30's up to full cap. They are all USGI as well. My take is that downloading is for when the mag will be loaded for an extended period of time so as to keep tension off of the spring. I havne't followed this practice yet and all of mine work well after thousands of rounds.

 

[Blackhawk 6]

Thirty-round magazines are down-loaded because they can be difficult to seat when the bolt is forward. Standard practice in the units I have been in was to load 28. There is nothing worse than struggling to seat a magazine, except thinking you seated one only to have it fall out of the magazine well when you fire the round in the chamber.

A quick way to check is press down on the rounds until they stop. If 28 are loaded the top of the rounds will be even with the bottom of the cut-out on the back of the magazine.

This is not an issue with 20-round magazines, at least in my expereince, hence no reason to down-load.

 

[Gator]

When I was in the service the standard practice was to load only 18 rounds in the 20 round mags. If you loaded 20 sometimes the first one or two rounds would not feed; the bolt couldn't strip them out of the mag. I think this was only a problem with mags that had new springs in them, but to be safe we loaded 18 in all of them.

When we got the 30 rounders the practice was continued... 28 rounds per mag only. It may not have been necessary, but it was already an established procedure and those can be hard to change.

 

[444]

To echo what Blackhawk 6 said, I was told the same thing during my Gunsite basic carbine class. You download the mag by two rounds because the rounds push against the bottom of the bolt. When doing a rapid magazine change, you want the magazine to latch up without having to slap the floor plate and all that.
This may or not be an issue depending on your individual magazines and rifle. However, it is a good practice just to make sure.
From a practical standpoint, if you can't solve the problem with 28 rounds, odds are that two more rounds arn't going to make much of a difference.

 

[Badger Arms]

Now, this may sound like a REALLY obvious question, but isn't the bolt open when you put a fresh magazine in in a tactical reload? I never have any problems, the bolt is already locked back! Maybe for inserting a fresh mag when the bolt is locked forward, but in a tactical situation you shouldn't have to worry about that.

Of course, if you want a full mag in the gun and you aren't empty yet, I can see how this could be an issue.

 

[444]

".....isn't the bolt open when you put a fresh magazine in in a tactical reload? "

Well, if we are going to get into terminology then no, in a tactical reload the bolt would be closed. If the bolt is locked to the rear, obviously your gun is empty (which is not good) and you need to do a speed reload, sometimes called an emergency reload.

 

[Blackhawk 6]

Maybe for inserting a fresh mag when the bolt is locked forward, but in a tactical situation you shouldn't have to worry about that.

Actually, in a tactical situation you try to avoid shooting your gun empty. Reload when it is prudent, not necessary.

 

[DevilDog]

My USMC training was 18 and 28 as well.

My current rule of thumb for any semi-auto with detachable magazines...

I load the magazine to its stated capacity. There should be enough room to almost load another round in it or more. If there isn't, it will be difficult to load it with the bolt/slide closed and there is a risk of damaging the magazine if forced.

Also, if a magazine is loaded to the point that you cannot depress the rounds in it at all, than there is probably too much pressure on the feed lips and if left in this condition, could and probably will lead to a magazine related malfunction.

 

[meh92]

I have malfunctions with 20 rounders loaded to capacity with Wolf ammo. The problem has never really surfaced with brass cases. I download mine because I like the ease of seating the mag on a closed bolt.