So I was most anxious to get my hands on the newest 10mm Glock: the 6-inch barreled G40 Gen4 MOS. And I wasn’t disappointed. Simply put, the G40 Gen4 MOS is a G20 Gen4 stretched out, and with Glock’s new MOS (Modular Optic System) added. Its 6-inch barrel gets adds 50 f.p.s. to the 200-gr. DoubleTaps and brings the aggregate muzzle energy up to 12,944 ft. Gotta git me one of these!
After sheer firepower, the second most compelling reason to trade in my G20 for G40 Gen4 MOS is the MOS system itself. It consists of a nearly 1/4-inch deep, full width flat machined into the top of the slide beginning just forward of the rear sight and extending almost 2 inches forward, ending just above the rear extremity of the extractor opening. There are two holes drilled and tapped into the top of the slide for attaching any of the four MOS mounting plates—numbered 05 through 08—that come with the pistol. It even includes a cover plate radiused and finished to mimic an uncut slide that fills in the slot when not using an optic. With the four MOS mounting plates available, you can quickly install any mini reflex sight from Docter, Meopta, Insight, Trijicon, C-More or Leupold. Whether for hunting or competition, there’s no question that the addition of a mini reflex sight is a huge benefit over open sights in obtaining maximum precision and accuracy.
The G40 Gen4 MOS is first and foremost a Gen4 Glock, so you get all the benefits of the most recent generation of the Glock platform: rough textured frame, dual captured recoil spring and guide rod, enlarged reversible magazine release and the modular back strap system. Our evaluation G40 Gen4 MOS came with a total of four back straps: 2mm and 4mm, both with and without extended beavertails. The extended beavertails extend 5/8” beyond the rear of the frame and help to control muzzle flip.
Other standard features include a white dot front sight, white outline “U” notch rear sight fully adjustable for both windage and elevation with the included sight adjustment tool, a cleaning brush, gun lock, plastic case, mag loader and three 15-round magazines.
In every other sense, the G40 Gen4 MOS is pure Glock. All controls and internals are placed, look and function like any factory Glock. Whatever you love or hate about the current Glock platform, you’ll likely love or hate about G40 Gen4 MOS. There isn’t a thing about the standard Glock platform that we hate, so the G40 Gen4 MOS was nothing but pluses for us.
During reliability testing we fired over 100 rounds on our Salute Products steel plate targets without a single malfunction of any kind. The reason I installed that Sprinco Recoil Reducer in my G20 was because those DoubleTap 200-gr. hard cast lead loads kicked like a son of a bitch and drove the slide hard into its stop with every shot. It worked well to tame perceived recoil and stop the slide slamming, but it’s not needed in the G40 Gen4 MOS because its factory double captured recoil springs and guide rod accomplish the same degree recoil reduction.
I shot my doctored up G20 along side the G40 Gen4 MOS with the same ammo and could tell no difference between the two pistols in terms of perceived recoil. Muzzle flip in the G40 Gen4 MOS was, however, significantly less than that of my G20, due, no doubt, to the added muzzle weight of the longer barrel and slide. Even so, G40 Gen4 MOS exhibited no perceptible muzzle heaviness, and tracked from target to target with ease.
We tested the Glock for accuracy at 25 yards using the factory open sights to keep the playing field level. The Glock showed a distinct preference for the DoubleTap 200-gr, Controlled Expansion JHP load, with a best group on 2.0” on the dot. The largest group measured 4.5 inches. The G40 Gen4 MOS is a great addition to the Glock line-up. See it at your gun shop (pricing was not available at press time), or contact Glock, Inc., Dept. OT;
Tel.: (770) 432-1202; Web: www.glock.com