The G39 In .45 GAP Is Powerful, But Ammo Choices Are Limited

Glock Model 39 45 GAP

The 39 makes for a powerful, accurate backup gun, but ammo choices limit it somewhat.

Primarily, .45 GAP ammunition differs from .45 ACP in terms of size. The GAP cases are shorter, and the primer pocket is smaller. At first look, the small pistol primer can look a bit lost in the center of the headstamp.

g39 45 gap

With this in mind perhaps it was only fitting that the Glock 39 was the smallest pistol in this test. Despite the barrel measuring just a hair longer than 3.4 inches, it looked and felt even smaller. The frontstrap only had room for two fingers, and the magazine basepad was flat. Releasing the magazine required getting the hand out of the way.

The G39 fed from probably the smallest of all Glock factory magazines. The double-column magazine stacks one round at the top, two pair more piled in staggered formation in the center with the last one offset to the right for a total of only six rounds. Despite being the smallest and tied with the Model 36 for lowest round count in the Glock lineup, our .45 GAP Model 39 did come with a couple of upgrades.

g39 slide release

The slightly oversized slide release on the 39 (black arrow) allowed us to pull back on the slide or hit the release to charge the pistol. The larger mag release found on the 30 (white arrow) would have been more helpful in dropping the magazine.


For one, the slide release was topped with a flat surface, which would have been handy on the G30. The second upgrade was the application of night sights front and rear.

Our overall shooting impression of the G39 was how easily it handled the .45 GAP ammunition. Recoil was pleasant, and the limited amount of grip area did not seem to be a disadvantage. Nor did the lack of available support area affect our benchrest session.

Firing the G39 from a sandbag rest we were able to accomplish the feat of landing identical average size groups measuring about 1.5 inches center to center with each choice of ammunition. Both the Federal Premium Hydra-Shok 185-grain rounds and the Speer Gold Dot hollowpoints printed groups ranging from about 1.3 inches to 1.7 inches across. The 185-grain FMJ rounds grouped in a pattern ranging from 1.0 to 2.0 inches.

g39 night sights

Our model 39 shipped sporting Glock brand night sights. Any accuracy issues we had with the gun was due to its smaller size, not its sight picture.



Power from both the hollowpoint defense loads was approximately 370 ft.-lbs. of muzzle energy, slightly more powerful than the larger Glock G30.

In our practical test we once again experienced the necessity for a careful loading technique. Due to the very short grip, the hand had to be held well out of the way. This accomplished, the magazines dropped smartly from the G39 on each run. Still, we felt that its limited grip area slowed down acquisition of the pistol and in some cases the ability to keep the gun balanced during fast offhand shooting.

Initial shots after picking the gun up and charging it averaged about three seconds. Total elapsed time for our two strings of fire averaged about 16.80 seconds. Under stress, both runs were hampered by our test shooter not being able to drop the magazine clearly past his palm. We suffered one miss on our first run and one more on our second run. We think this gun could be improved with the addition of a pinky rest on the magazine and the addition of Glock’s oversize magazine release button.

What impressed us most was the power and accuracy of the .45 GAP ammunition. We asked a Houston firearms retailer if 45 GAP pistols were selling well. He said, "All Glocks sell. But, I haven’t needed to order more .45 GAP ammunition since it came out." Perhaps if this caliber had been introduced before .40 S&W, then 45 GAP might have become the dominant defense round for polymer pistols. Its bigger brothers, (the G37 and G38 pistols), may be the way to go for primary carry, but the G39 should make a superb backup gun.

test gun

Originally Published In January 2007.


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