The Father of the PDW, Capt. Mack W. Gwinn, Jr., Passes Away at 79

Mack Gwinn, Jr., firearms design innovator and accomplished inventor holding multiple patents, has died after a long illness.

Capt. Mack W. Gwinn, Jr. (US Army Ret.)
Capt. Mack W. Gwinn, Jr. (US Army Ret.)

Hermon, Maine (March 2024) – Hydra Weaponry CEO Mack Gwinn III has announced the passing of his father, Capt. Mack W. Gwinn, Jr. (US Army Ret.) on March 11, 2024, surrounded by family, after a long illness. As part of his legacy, Hydra Weaponry is Maine’s largest firearms employer manufacturing the modular MARCK-15 Hydra® Weapon System, the new Hydra 10, and the BMP-23 pistol, one of Mack Gwinn Jr.’s earliest firearms designs that later became known as the Bushmaster pistol and the Bushmaster rifle.

As the son of a retired Army officer, Mack Gwinn Jr. joined the Army and served in the Special Forces (Recon) during the Vietnam War era. He received, multiple Purple Hearts, the Bronze Star W/V , along with the US Army Meritorious Service Medal, Air Medal, and Army Commendation Medal.

Upon his return to the US, Mack Gwinn Jr. had an idea. Gwinn, Jr. took the design idea from the Air Force Individual Multi-Purpose weapon system, a scrapped project by Colt, the IM-221, a stockless, gas-operated bull-pup pistol, and created a civilian personal defense weapon that radicalized firearm design. The IMP-221’s purpose was to provide airmen with a lightweight, compact weapon system used for survival and in combat. When the Colt project IMP-221 using the .221 Rem. (5.56x36mm) caliber failed due to accuracy issues, the Air Force scrapped the project. Gwinn, Jr., fresh out of South East Asia, started Gwinn Firearms and after securing the rights to the IMP-221 design, worked to revamp the arm pistol for the civilian market. With much of the initial design intact, Gwinn, Jr.’s design changes initiated massive changes in future product design considerations. First, instead of the .221 Rem, he chose .556 NATO as the caliber, and more significantly, he redesigned the lower receiver to accept existing AR-15/M16 magazines, a trend that continues today with multiple manufacturers. His arm pistol became known as the Bushmaster Arm Pistol. Besides, the Bushmaster Pistol, Gwinn, Jr. developed a Bushmaster rifle. Then, in 1976, Gwinn Firearms was sold and became Bushmaster Firearms.

Mack Gwinn, Jr. went on to found other companies to build on his ideas for advanced technologies to serve the military and private sector. Under the MGI banner, he designed what he considered the rifle system he wished he had while serving in Vietnam; a modular system that could quickly and easily interchange calibers in the field so that the soldier could convert from a long-distance shot to a more powerful short or mid-range caliber. The modular system he invented benefited soldiers, law enforcement, and civilian marksmen with the ability to carry multiple calibers for a myriad of missions, whether on their person or personal vehicle. His son, Mack Gwinn III, also a US Army Special Forces Veteran, came aboard MGI and eventually took the helm. MGI eventually transitioned into Hydra Weaponry, the firearms company that today is bringing about the firearms systems created a generation ago by the man many consider the father of the personal defense weapon.

His curiosity, intelligence, and background led him to work on a variety of projects, including the Sting vehicle as a replacement for the US Army Jeep, two versions of a remote ground security vehicle, and under Ordinance Technology Inc., he created the SSP-86 target pistol with the Canon-style breach-action. Under Muzzle Lite Inc., Mack Jr. designed bull-pup stocks for the Mini 14 and the 10/22. He developed recoil reduction systems for Counter Poise. He created and sold/licensed the .50 caliber QCB system to FN. He developed 12ga. adapters for 37mm and 40mm launchers. As Firepower Inc., Gwinn Jr. developed the 75-round magazine and eventually the 90-round magazine for MWG Co.

For more information on Hydra Weaponry, visit the new website at

About Hydra Weaponry:

Headquartered in Maine, Hydra Weaponry has 50 years of firearms innovation in its DNA. Starting with the development of the Bushmaster pistol, rifle, and submachine gun, the Gwinn family has set a high standard of designing innovative firearm platforms built around the actual needs of tactical operators, often fighting in extreme conditions and environments. The MARCK-15 Hydra Modular Weapons System is the ultimate modular platform that designer Mack Gwinn, Jr. created to meet the criteria of modularity, durability, consistent performance, accuracy, and affordable. Hydra Weaponry is the future of small arms.

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