Maxim Defense PDX™ SBR



Caliber 5.56 NATO/7.62x39mm
Barrel length 5.5in
Overall length 18.75in
Weight (empty) 5lbs, 11oz
Muzzle brake Maximum Defense HATEBRAKE muzzle booster
Trigger ALG Combat Trigger
Stock Maximum Defense SCW stock system
Color Black/Arid

Maxim Defense Industries, an information tech company based in St. Cloud, MI, recently introduced their PDX short-barreled rifle at the 2019 SHOT Show in Las Vegas.

About Maxim Defense

Maxim Defense is an information and development company whose goal is to provide to the military, law enforcement and first responders the next generation of tools and equipment to succeed in today’s most extreme environments. The company primarily engages in small arms manufacturing focusing R&D on producing better, lighter and more reliable weapons and accessories. Maxim seeks to improve and enhance existing weapons platforms alongside developing cutting-edge technologies.

SOCOM Requirements

U.S. special operators are in the market for a new small assault rifle. On March 9, 2017, US Special Operations Command (SOCOM) posted a request for information regarding a new personal defense weapon (PDW) on FedBizOpps, the federal government’s main contracting website. All interested companies would have to provide information on a kit that uses the standard M4A1 lower receiver as the core of the gun.

The request went on to specify that the weapon could not be more than 26 inches in length with the stock extended, be no more than 7.5 inches high and come in at 5.5 pounds or less. With the stock folded, SOCOM required that the overall length dropped to 17 inches. The preferred length would be 15 inches. This weapon would be ideal for troops engaged in close-quarter battle, especially in confined spaces, as well as be easily deployable when carried by either vehicle or helicopter crews.

The Maxim Defense PDX™ is an answer to the SOCOM request. It’s a weapon that is based around the Maxim SCW stock system that has a total overall length of 4 inches when closed but extends instantly to a solid, shoulder-mount weapon. It has no buttons to operate and can be instantly deployed to a preset length controlled by five detents in the operating rods.

In this configuration, for an individual the weapon will have to be transferred with a $200 tax stamp and an ATF form as a Short Barreled Rifle. However, Maxim Defense has said that the PDW will be available with their proprietary pistol brace which removes the requirement for a stamp.

Barrel length is a short 5.5 inches. Seeing as how it’s chambered for either 5.56 NATO, or 7.62x39mm, recoil or short-cycling could be a problem. This is where Maxim’s patented HATEBRAKE comes into play. More than a muzzle brake, the HATEBRAKE muzzle booster is designed to regulate exhaust gasses to aid in cycling the weapon. Side benefits include a redirection of the sound signature, decreased muzzle flash and improved accuracy. The HATEBRAKE installs with a 3/8 drive socket from the front. This enables it to be installed without removing the handguard. The HATEBRAKE uses tapered threads to lock in place on the barrel. Its design allows it to be used with M-Slot-compatible handguards.

A note on accuracy: Part of the requirements for the PDW is an accuracy at 300 yards of 8-inch groups. The possibility that this firearm will be used at such a distance is slight. Its mission is more in line with the old World War II M1 or full-auto M2 carbines. At 100 yards, the PDW can deliver groups between 3 to 5 inches, sufficient for its intended purpose as a close-range defense weapon.

HATEBRAKE Specifications

Caliber 5.56 NATO; 7.62x39mm (9mm in other uses)
Thread pitch 1/2×28, 1/2×36, 5/8×24
Material 17-4 H900 Stainless/ 6AI-4V Titanium
Finish Black diamond-like coating (DLC)
Weight 4.6oz
Length 2.4in
Diameter 1.75in