When and why did the 30rd mag come about?

[mini4m3]

I'm at work right now but you can find pictures of guys running the XM177 late 60s with 30 round mags in them.

edit* found one really quick


Note the 30 round on the left

[sdacbob]

When I enlisted in 1986 my first issue was an M16A1. 30 rounders were already well into the system at that time.

M16A2's were still not full integrated at that point. I remember seeing 30 rounders as early as 1983.

I enlisted in 1976. The M16A1 was in use then. Most of the mags we had were the 20rd and we had the old canvas M14 mag pouches and eventually the nylon 20 rds pouches. 30rd mags were hard to come by and were horded. I was in a Cav unit then and not an Infantry unit. When I went to Europe in 78 we had 30 rd mags.

[patrick sweeney]

Ok, all the gory details, as best I remember without digging out the library.

The originals were twenty rounds simply because the Stoner rifle was a 1950s design, and that's all anyone "needed" at that time. The USGI 20-round magazine is essentially an M14 mag, writ small.

We get sucked into SEA in a big way, and find that the grunts don't like having "only" 20 rounds, when the bad guys have 30. So, the word goes out: we need 30's.

One problem: the on-again, off-again nature of the M16 acquisition has meant Colt made slightly varying iterations of the rifle. They all work with 20-round, straight mags, but some won't accept a constant-curve 30 round magazine.

By this time Colt is in enough hot water over the m16, that they don't need another black mark on the black rifle. And, they can't really tell DoD that some of the rifles they sold the government aren't up to snuff.

So, they design a straight-then-curved 30 round magazine, and struggle for a generation to make it actually work.

And yes, a Magpul PMag30 is a constant-curve magazine inside of a straight-then-curved shell. Clever of them.

Why is a 20 not curved? The taper of the cartridge stack doesn't add up to enough that you can't handle it with planned carrier tilt. the 30 is too much, and thus requires a curve.

And those 20-round mags that look like shortened 30s? Exactly. Take the stamping equipment, and make a tube long enough to hold 20, but not thirty, and don;'t change anything else. If you;re a magazine company, and you started making 20s, and then added 30s, two different magazines makes sense. If your company started only ever making 30s, modify what you have, rather than try to re-invent the wheel (or 20-round mag.)

[Larry Vickers]

Remember the arrogance level in the US Ordnance Corp in the 1950's - if you have never read anything about the M14/FAL saga you should as it sets the stage for the M14/AR 15 saga that followed;

The USA defeated ( I'm sure we felt singlehandledly ) both the Nazis and the Japanese with a variety of small arms but mainly a clip fed 8 shot rifle ( M1 Garand) - the instant the MP43 hit the field ( mainly against the Russians) the Garand was obsolete; we honestly never got that thru our head until Vietnam when we faced the AK- the Russians on the other hand got that memo early on and developed the AK to equip their army

The 20 rd mag of both the FAL and M14 was 2.5 times the firepower of the 'war winning' Garand so I am sure it was felt to be more than enough- thus when the AR was developed the designers thought WAY out of the box but not in regards to magazine capacity; they had the same 20 rds is enough mentality as everyone else at the time

The Stoner 63 was a weapon system that was developed by Stoner for Cadillac Gage after he left Armalite- by then he obviously got the memo on magazine capacity and designed a 30 rd magazine, and a pretty good one at that ( influenced by the AK mag), as a baseline mag for that weapon system- hence the constant curve

Alas only until Magpul and the Pmag was a constant curve ( more or less) possible for the AR- remember up until the Pmag the plastic AR magazine was a total joke- they had been tried and found seriously lacking so when myself and countless others saw the Pmag for the first time at SHOT I laughed as I assumed it would fail- and I was as wrong as wrong could get!!

That being said let me give you my advice for Pmags; use black ones, window or non window, for serious purposes - to me they are the most durable - do not use the brown ones for anything other than plinking as I have seen too many of them crack

If you use them hard for months on end in my opinion after about 6 months you should pitch them and buy all new mags; for the cost that is a bargain

And last but not least if you are going to be using your AR in extreme cold use metal mags- and use a good cold weather lube on your weapon like TW25B

Cheers

LAV

[Iraqgunz]

Larry,

I was hoping you would drop in at some point. You are exactly correct about the Ordnance Corp. attitude and there have been several good articles over the years in Small Arms Review by prominent designers and engineers who bemoan the fact.

[ASH556]

Great info Mr. Vickers, thanks!

[BHPmk3]

Does anyone prefer the 20 round magazine? I personally like using it, especially when shooting a match or practicing while in the prone position. Don't get me wrong though, the 30 rounders certainly look cool!

[Iraqgunz]

Having 30 rounders has nothing to do with looking cool. Yes, the 20 rounders have a place, but I'll use the 30's whenever possible.

Does anyone prefer the 20 round magazine? I personally like using it, especially when shooting a match or practicing while in the prone position. Don't get me wrong though, the 30 rounders certainly look cool!

[BHPmk3]

Having 30 rounders has nothing to do with looking cool.

I was referring to the tactical couch soldiers who outfit their guns with all the latest gear so they can play army, but then can't hit the broad side of a barn when they visit the range because they don't understand the basic principles. I'm figuring you know the types I'm talking about because we've all had the misfortune of running into these clowns...

[Axcelea]

Just throwing it out there since no one has mentioned it, although it was mentioned as a plus for 20 rounders.

I heard part of the decision around a 20 round mag was for shooting in the prone position.

As for switching to 30 rounds, I think it has been nailed "they have, I want".