KCI 15-Round M-1 Carbine Mags: Affordable Reliability

So, you’ve bought yourself an M-1 Carbine. Congrats! The Carbine is one of the handiest and coolest surplus rifles you can buy. If you’re like me, you’ll get immense pleasure from owning and shooting this historical firearm. But there’s one problem: the original GI magazines leave much to be desired. The American war industry never produced a reliable Carbine magazine. Most soldiers just threw them away when they were empty. There were plenty more where those came from. But today’s civilian Carbine owners expect more from their magazines. KCI offers, in my humble opinion, the best option for new Carbine mags.

M-1 Carbine KCI 15-round magazine
The KCI M-1 Carbine magazines are better than the original GI mags. (Author’s Photo)

Unforeseen Versatility

Introduced just before World War II, the M-1 Carbine was originally intended for rear echelon troops like truck drivers. It gave them a more effective weapon than the M1911 pistol it replaced in that role without saddling them with a full-size infantry rifle. It was more accurate at range than the 1911, and the .30 Carbine cartridge’s energy compared favorably with the .357 Magnum at 100 yards. And training those troops on the Carbine was easier and faster than with the 1911.

The Carbine was light and handy, weighing only 5.2 lbs. with an 18-inch barrel. That soon attracted combat units. By 1944, the Carbine was being issued to paratroopers, tankers, artillery and mortarmen, engineers, and even frontline infantry units. It never replaced the M-1 Garand, nor did the Army or Marines try, let’s be real, but the Carbine soon expanded beyond its original role.

Some 6.1 million M-1 Carbines were produced during and immediately after World War II, more than any other American wartime small arm. So many Carbines were made that the US military never made any more, even though the gun served into the early years of the Vietnam War. Many were upgraded to the select fire M-2 version, though most remain in their original configuration.

M-1 Carbine with KCI 15-round magazine
The M-1 Carbine is a great rifle that’s tons of fun. (Author’s Photo)

KCI 15-Round M-1 Carbine Magazines

The M-1 Carbine’s standard capacity is 15 rounds, which in its day was only bested by pistol caliber submachine guns. It had twice the capacity of the M-1 Garand, though the Garand’s 30.06 Springfield cartridge was far and away the superior combat round. But the Carbine did its job. By war’s end, the M-2 version boasted 30-round mags, which were compatible with the original M-1 as well. I’ve reviewed the 30-round magazines elsewhere.

KCI makes a solid 15-round Carbine mag that is better than the original GI mags. I have one of those old mags, but I don’t use it. It’s not reliable. The KCI mags are. Here are the basic specifications:

  • Caliber: .30 Carbine
  • Capacity: 15 rounds
  • Weight 0.2 lbs.
  • Body Material: Steel
  • Spring Material: High Carbon Steel Music Wire
  • Finish:
  • Cation Electrodeposition Coating
  • Compatible with M-1 and M-2 Carbine configurations
  • Some have a witness hole at the bottom. Some don’t. I never use it so I don’t care.
  • Lifetime Warranty

I bought my first Carbine about a year and a half ago, as of this writing. The GI mag it came with was not good. Looking for other options, KCI had the best reviews, so that’s where I went. I’ve had no reason to regret that choice. I still have the GI mag because of what it is, but I never use it. The KCI mags are better.


The KCI 15-round mags have run quite well for me, though I should note they seem to need a short break-in period. But that doesn’t last long. They usually run fine after 45 or 50 rounds. I’ve never had a problem once they’re broken in. The magazine spring is strong, and the follower is solid. The lock back function always lets me know when my Carbines are empty.

KCI M-1 Carbine 15-round magazines
The KCI M-1 Carbine mags are inexpensive, and they work. Note that one mag has a bottom witness hole and the other does not. No big deal to me. (Author’s Photo)

Loading the mags is a bit of a learning experience. The feed lips are kind of sharp and will get after your thumbs if you don’t load them properly. I quickly learned to press the rounds down from the top instead of sliding them in from the front like a pistol.

I run these mags pretty hard. My Carbines are fun, and I appreciate their history, so I occasionally throw them into my training rotation. I run the same drills that I do with my ARs and AK. That means lots of mag changes. The KCI mags have held up well so far, with the only noticeable wear being the finish where they slide in and out of the mag well. The bodies, springs, and followers do their jobs and I have tons of fun with my Carbines because of it. Let’s face it, no matter the coolness factor, a gun that won’t load because of crappy mags is no fun at all.

The mags occasionally don’t drop clear without some help. Whether that’s their light weight or the rifle’s ejection mechanism, I can’t say. But you deal with it. I’ve learned to reach for the spent mags like I do with my AK. Honestly, the hardest thing to learn about Carbine mag ejection is differentiating between the mag release and the safety. It just takes muscle memory to hit the right button.

Carbine Recoil Springs

An important note about initial performance. If you are new to the M-1 Carbine and having feeding problems, it may not be the magazines. I had trouble at first too, but a little research revealed that many surplus Carbines need their recoil spring replaced. Even if they were arsenal refurbished, those springs could still be almost 80 years old.

I replaced my first Carbine’s recoil spring, and it immediately resolved my issues. Wolff Springs has them for less than 10 bucks, or you can get “Rifle Service Paks,” with every spring for the rifle, for less than $25.00. I took that route. When I bought a second Carbine, I immediately bought another Rifle Service Pak and replaced the recoil spring. It’s simple and takes about five minutes.

M-1 Carbine recoil spring
Replacing the Carbine’s recoil spring (outlined in white) will likely improve its performance. It’s easy and inexpensive. (Author’s Photos)

A Good Value

KCI M-1 Carbine mags are a good option for not much money. I’m happy with the value I’ve gotten from mine. They are solidly constructed, and they work. Just remember to give them a few rounds to break in. I’ve never had any compatibility problems with either of my Carbines, both of which are original GI models, manufactured in early 1944.

Very occasionally, I’ve run across a round that won’t feed. I’ve learned to try it in different mags to see if the mag or the round was faulty. Every single time, the round has failed to feed in every mag. In each case, the round fired when I inserted it directly into the chamber. I can’t say why that is. But in a year and a half, it’s happened less than five times. So, it’s really not an issue for me, and it’s not like I haven’t had similar things happen with other firearms.

So, if you’re looking for good mags for your M-1 Carbine, give the KCI 15-round mag a try. It’s worked great for me, and I expect that to continue for years to come. And what do you know? Gun Mag Warehouse carries them, so you’ve even got a supplier. You’re welcome.

William "Bucky" Lawson is a self-described "typical Appalachian-American gun enthusiast". He is a military historian specializing in World War II and has written a few things, as he says, "here and there". A featured contributor for Strategy & Tactics, he likes dogs, range time, and a good cigar - preferably with an Old Fashioned that has an extra orange slice.

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