Getting 7.62x39 to be reliable in an SBR has been a challenge … until now.

The Maxim Defense PDX is one of the coolest guns to hit the market recently, and we got a chance to take it for a test drive at F.I.R.E. Expo in Florida this year. This little gun features the firepower of an AK while reaching just 18.75 inches in overall length. It’s designed for close-quarters combat and first response, with the small size making it easy to maneuver in tight spaces. It is offered in three calibers: 5.56 NATO, 300 BLK, and 7.62x39. 

This is a custom-built gun for small spaces, which should come as no surprise. The Maxim Defense PDX was originally designed by a tanker, who had to live and fight from inside confined spaces.

The PDX was designed by a former tanker, who understands the value of a compact weapon in a confined space like this M1 Abrams tank. (Photo: Sgt. Arturo Guzman/Army National Guard)

This makes the PDX an excellent compact gun fit for fighting in the tight hallways of a building or storing inside your truck. The small size also makes it suitable for backpack carry or for LEO looking to add additional firepower to their tool chest. 

The bolt carrier group and the buffer are uniquely built to allow such a short gun to cycle ammo like 7.62x39. (Photo: Taylor Thorne)

Though the other calibers are quite fun, 7.62x39 is what makes the PDX special. This is a rare example of an SBR that has proven to be reliable with AK rounds. Maxim Defense achieved this by having a unique bolt carrier group, where the buffer weights actually sit partially inside of the BCG. This allows the compact gun to fully cycle. The gas system works perfectly with their HateBrake muzzle device or a suppressor. Swapping between the two requires no tuning. 

Shooting the PDX is a dream. Felt recoil is very minimal for such a small gun shooting a powerful cartridge. If you compare it to shooting a full-sized AR chambered in 5.56, it is basically the same (if not a little less recoil). This is particularly impressive given that an SBR typically has more felt recoil. 

The HateBrake helps prevent gas from interfering with your ability to see and shoot. (Photo: Taylor Thorne)

The HateBrake muzzle device does an excellent job burning up all the excess gas, so you’re not suffering with gas in your eyes when shooting. The ALG trigger also has a nice, clean break. Overall, the PDX feels very balanced. It would make a great gun for anyone looking for a subcompact with serious firepower. 

The addition of the Helios suppressor makes it even more suited for fighting in confined spaces, though switching to the suppressor does lead to much more gas. But the reliability of the gun was still solid with the suppressor. 

The PDX is beyond compact. It’s shockingly compact for a gun that can also cycle 7.62x39 reliably. (Photo: Maxim Defense)

The fact that this compact package can fire a round like 7.62x39 is impressive enough on its own. Its ability to do it reliably with and without a suppressor makes it a gun you just don’t want to give back after testing. Plus, the controls on the PDX will be familiar to those accustomed to using AR-style platforms, though the assembly and disassembly are different.

The PDX is also offered as a pistol with a brace. So if going through the tax stamp process isn’t of interest, no worries. Choose your caliber, color, and decide between the pistol or SBR configuration. Either way, you’ve got yourself an incredibly powerful, reliable firearm for close quarters.