Review: Glock's New Slimline Magazines

The introduction of a new product at NRAAM is usually conducted with great fanfare. What may turn out to be the one of the most important debuts of 2026 came in the form of an email, followed by the display of samples at the Glock booth. The Austrian titan just a few months ago had seized the industry’s attention with the introduction of the Gen 6 Glocks. Momentous, to be sure, but the later introduction could impact the concealed-carry market nearly as much. Glock introduced its own 15-round magazine for its slimline models G43X and G48.

Glock’s little G43 was a big deal when introduced, but it was eventually supplanted in firepower in a big way. SIG Sauer’s P365 and Springfield Armory’s Hellcat offered flush-fitting 15-round magazines, while the Glocks most-capacious slimline models, the G43X and G48, could accommodate only 10-rounders. Both Glocks did well in the marketplace, though not quite as well as the P365.

A small, independent company called Shield Arms came to the rescue with its S15 15-round magazine for the slimline Glocks, but there were a few growing pains with it that necessitated three generations of the units before they functioned just right with all Glock G43Xs and G48s. However, despite the innovation, the Shield Arms’ magazines—being metal and having a release cut-out rather than an indentation—require Glock owners to replace their polymer magazine-release button with a metal one; not a big deal, but a likely obstacle for some purchasers desirous of simplicity.

That this segment of the firearm market is crucial, be aware that the SIG P365 is the single bestselling handgun in America and the Springfield Armory Hellcat is that company’s bestseller. We’re talking big money, and Glock’s vaunted G19 had long led the personal protection handgun market—until the P365 ascended the throne. (The G19 is still a top seller and the G43X is no slouch in terms of sales.)

Glock sent me a couple of the magazines. They are rumored to be produced by Mec-Gar, an OEM supplier of magazines to many manufacturers, but outsourcing is not something Glock is known for. The fact that these new units are not produced by Glock is immediately apparent as the tubes are made of steel, whereas Glock magazines have long been polymer with metal inserts. In addition to the all-steel tube, the new magazines have a significantly thicker base pad compared to the originals.

Like the originals, though, they have an indentation as the magazine-release notch rather than a cut-out like the Shield Arms’ S15. That means you can stick with the original, polymer magazine-release button rather than having to replace it with a metal one. In fact, if you’ve already replaced your magazine-release button, you’ll have to reinstall the polymer original if you intend to go with the new Glock-branded option.

Putting 15 rounds in a space that previously accommodated only 10 means something has to give—and that will likely be your thumbs. The new magazines are hard to load, so hard, in fact, that you pretty much have to use a loading tool.

Once inserted in the pistol, that thick base pad makes its presence known, protruding approximately a quarter-inch more than did the original. Is that a lot? Yes and no. Many daily concealed carriers obsess over the concealability of their EDC guns, sweating every little fraction of an inch. On the other hand, the G43X, with its larger grip, outsells the standard G43.

On the range, the new magazines demonstrated teething problems typical of new magazines—except ones that say “Glock.” In the first 50 rounds there were a couple of failures to feed and two failures to lock back the slide after the last shot. As indicated, such would be no big deal with many other brands, but it has caused some minor hand-wringing among Glock owners unused to such things. Me, I’ll just keep shooting them on the range until they go each go 100 rounds with my carry ammo without a malfunction, then I’ll put them in my EDC gun and not think twice about it. That’s SOP with most new guns/magazines, though I had gotten away from it with Glock pistols.

Glock’s slimline pistols are unaffected by the new Gen 6 enhancements. It’ll be interesting to see if the new magazines boost sales of the G43X over the G19 and, ultimately, over the company’s competitors. Between the new generation of standard-size Glocks and a 50 percent capacity increase in the magazines of two of the slimlines, the company has likely seriously increased sales firepower.