Anything wrong with exclusive use of 20 round USGI mags as go to?

AR/M4 AR General Discussion
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Anything wrong with exclusive use of 20 round USGI mags as go to?

There was a long thread on AR Technical of guys going back to USGI aluminum mags for many different reasons. I prefer metal mags (USGI) for their compactness and have quite a few USGI 20 and 30 rounders. All my 20’s are USGI straight Colts. All my 30’s are OKays that have been upgraded with Magpul Gen 2 followers.

As everyone knows, a USGI mag fully loaded with 30 rounds can be slightly difficult to lock in with bolt forward. To insure easier and positive bolt forward reloading, most SME’s recommend the 30’s to be loaded to 27 or 28. Some even recommend 28 rounds in the newer mags (Magpul, Lancer, etc.) which are slightly longer than USGI metal mags, and “should” have no problems loading to a full 30 and loading bolt forward. The newer mags were supposedly designed for a full 30 round loading, yet there are continued reports of people who have difficulty loading a bolt forward AR with a full 30-round mag.

I keep a sizeable stash of go to 20 round USGI straight mags fully loaded to 20 and find they insert and lock into all my Colt AR’s VERY easily and VERY positively with bolt forward.

I am considering going with straight 20’s exclusively. My rationale is they are super compact. Substantially more so than 20’s from Magpul, Lancer, or even curved metal 20’s. A loaded AR is more compact. Spare mags can be carried in more compact pouches and a joy to manipulate during fast reloads.

I’d rather have mags loaded with 20 than much larger mags holding just 7 or 8 rounds more.

They were the original mag designed for the AR. Although my 30’s have been just as reliable (on the range) as the 20’s, the 30’s with it’s compound curve, was a design afterthought and most weapons experts agree the AR mag is the weakest link in the system.

This is kinda analogous to piston AR’s. Some piston designs work. Some designs work better than others. But most SME agree, the DI AR works best the way it was designed. Replace the words “piston” with 30 round mag and “DI” with 20 round straight mag. I understand AR improvements like flattop uppers, but I’m talking about the original design function.

While I won’t get rid of my 30’s as a just in case, do you guys see any issues/major disadvantages with going with 20’s exclusively for HD/SHTF? Anyone else considering the same?

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Nope.

That is, I don’t think there’s anything wrong with relying exclusively on USGI twenty round straight aluminium magazines. Then again, I’m the “Square Range Kid.”

There was an interesting thread by some jerk called MoonlightAgain recently about twenty round magazines. I picked up some of the Lancers, and now you’re tempting me with GI mags.

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I’m a special snowflake who prefers the USGI aluminum twenties also.

Lighter weight, more compact, and from what I hear: more reliable than thirties.

I’ve not logged enough rounds to know if that’s just an urban legend, but you sure don’t see people bitching about the twenties (except for PMAG twenties).

Could just be that fewer people use the twenties and so there are fewer complaints, but it’s interesting to me that you don’t see attempt after attempt to improve reliability with different followers.

I keep my “humping the bush” kit stocked with twenties for when I have to hike the fence line at my ranch.

No one’s ever corrected me on the practice, but I still download my twenties two rounds and only load them to eighteen. I may just be acting out another Vietnam-era myth (like staggering your bolt ring gaps), but like I said: no one’s ever told me not to.

The only thing I don’t like about the twenties is that there is less there to grab under stress. If I were facing a known firefight in advance or something, I’d switch to the thirties, but for every day use I prefer the twenties.

Long live the Roaring Twenties!

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The USGI 20 round mag is a little better design. Numb nutted idiots on the other site used to credit this to the alloy follower. But the plastic follower NTMTGs run just as good.

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My go to stash is preloaded to a carefully counted 20 rounds. No overstuffed mags to malfunction here. I believe the 18 round thing was to insure mags were not overstuffed with 21 rounds. It also helps that most 223/5.56 ammo is loaded in 20-round cardboard boxes. It’s also easier to know the top round of a fully loaded mag (20 or 30) should be on the right if holding the mag with bullets facing away from you.

No one complains about the difficulty of not enough to grab of a standard 15/17 round pistol mag when reloading a pistol . Grabbing a twenty round AR mag is much easier than grabbing/reloading a 15/17 round pistol mag.

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I prefer 20 round mags in general and good GI mags are usually pretty cheap. I am not ever going to fire full auto (a no go in my state) and I am not in a combat zone so needing more then the 18 rounds my department policy states I load in my mag would pretty much never happen. I still carry an extra mag just in case, but my mags are almost all 20 rounders except for the few 30s that get issued to me.

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I cannot recommend the Lancer 20 round AWM.

I love 20 round mags for their compactness. I love Glocks with plastic frames. I LOVE the idea of translucent mag bodies to monitor rounds left. The Lancer AWM is a plastic, translucent 20 rounder. What’s not to like? I ordered two of them from Brownells to try out.

Because of a bad experience with a couple of similarly designed Ramline 30 round translucent mags, where the mags would water fountain 2 or 3 or more rounds, out of the top of the mag when slapping into the magwell. I was a bit cautious but hopeful 25 or so years have improved translucent AR mag design.

I fully loaded both mags to 20. I “settled the rounds in the mag” in the usual way and sure enough, 1 or 2 rounds would water fountain out of the top of both mags. The AWM’s have wrap around metal feed lips, so I didn’t think that would happen. I “slapped” the mags into several Colt AR’s with bolt carrier locked back, figuring the mag well would “reinforce” the wrap around feed lips to reduce the water fountain effect. Nope….one or two rounds would pop out into the open AR action. I repeated the test numerous times with the same result. YMMV.

I suppose 1 or 2 pop outs per slap are better than 2 or 3 pop outs a generation ago. I suppose they would be great mags if they were loaded gently and NEVER slapped into an bolt-locked-back AR. Without shooting them, I returned the mags to Brownells with a comment on the return receipt. I don’t need to see if they are shooting reliable as I already have reliable USGI mags. I REALLY wanted the translucence feature. I repeated the same test with 20-round and 30-round USGI mags with the same slapping force, if not WAAAY harder, and no rounds popped out.

Furthermore, the 20 round AWM’s are significantly longer than 20 round straight mags. Nevermind the significantly thicker baseplate area verses straight mags. I took photos of this size difference as a reminder.

I believe the dimensional restrictions of the AR mag well prohibits the thickness required to allow a reliable clear plastic mag. (AUGs use MUCH thicker translucent plastic in their mags.) With present technology, clear plastics is < colored plastics < black plastics is the rule. I believe even Magpul recommends their black mags are stronger than their “other colors” mags.

I don’t know about your intended 300 Blackout use. YMMV. Good luck, but test those mags if you intend any serious use.

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So far I’ve gotten one bad aluminum 20-rounder in FDE from Brownells (apparently they’ve discontinued these). The mag body was just slightly oversized enough to fit the mag well tightly and not drop free.

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Thanks, man. Now I’m going to go beat my head against the wall. Then I’ll do some more testing. Hmm, twenty round GIs . . . .

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Any real differences between straight 20rd magazines and those with a slight curve to them?

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I don’t know about fewer people. The 20-round USGI mag was used by plenty of people during most of the Vietnam conflict, from issuance to about 1969. Even when the M16 needed upgrading to M16A1, they didn’t change the specs on the mag but to the rifle itself. Even designing the 30-rounder wasn’t because of reliability issues with the 20, but because of the demand for greater firepower.

Great comment on improving reliability with different followers on 30-rounders! I agree.

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The “curved” 20’s are made from shortening curved 30’s. The manufacturers are just cutting costs with the same mag body die as the 30. As a result, the curved 20’s may suffer from the inherent/perceived less reliability of the 30’s which share the compound curve design.

I also don’t know why the curved 20’s need to be so much longer than the straight 20’s, but they are significantly longer while holding the same number of rounds. I believe a mag design for 5.56mm ammo can go up to 25 rounds, but need a curved design after that. (i.e. FAMAS has a straight mag body with a 25 round capacity.)

Also if you are looking for the MOST compact mag, the original 20-round USGI is it. Compare to a 9mm (approx. same cartridge rim diameter as 5.56mm) Glock mag, which holds the most rounds for it’s length of any pistol mag, barring the single vs double feed of an AR mag. You cannot get more compact a mag that holds 20 rounds of a cartridge the size of the 5.56.

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I meant fewer people on the worldwide interweb. :smiley:

Great comment on improving reliability with different followers!

Thanks. That’s actually what convinced me. The laments over the new tan follower GI mags made me think going old school was a no-brainer for civilian use.

BTW, the comment about curved 20-rounders: I believe someone said that’s a C-Products abortion. They basically just cut the 30-round mag body down for 20 rounds.

I started this thread a while back:

“USGI Vietnam 20-round mags: GTG or not so much?”

(having trouble copying the link for some strange reason)

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No one complains about the difficulty of not enough to grab of a standard 15/17 round pistol mag when reloading a pistol . Grabbing a twenty round AR mag is much easier than grabbing a 15/17 round pistol mag.

Well I suppose if you index an AR mag the same as a pistol mag then you may be correct. ( I know many do it) But if you use the “beer can” method regardless of which direction your rounds face it would be difficult to compare the two completely different methods. I can see the argument of not enough to grab during reloads.

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The thing is a lot of mag pouches are designed around the thirties. The twenties sink lower into the pouches so they are harder to grab.

There’s also less to hold onto for a stress reload.

Still, you can’t beat the light weight and compactness.

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Been done.

https://www.m4carbine.net/showthread.php?t=113518