One thing I’ve learned through my years of writing about guns and self-defense is that wartime often drives firearm innovation because manufacturers are spurred to design military arms with specialized functions.
Lightweight Icons: M1 Carbine and M16
Some of those designs became legendary. One lasting firearm was the lightweight M1 Carbine, designed as an easy-to-carry option for rear-echelon troops that was effective out to 100 yards. The battle-ready M16 rifle also remains a staple, after it began as a lightweight, accurate, full-auto weapon for airbase security in Vietnam. It even replaced the heavier M14 for front-line troops.
However, not all weapons developed in wartime fared as well. One experimental weapon design was the DIP Aircrew Survival Weapon. Designed at the U.S. Air Force Armament Laboratory at Eglin Air Force Base, the DIP was built to replace .38 Special revolvers and 1911 .45s for downed pilots.
The DIP blended features of the M16 and AK-47 into a compact, gas-operated “pistol.” It was originally chambered in the civilian .221 Fireball cartridge, a shortened .223 round that saved magazine size and weight. Though thoroughly tested and found to be reliable, the DIP was eventually rejected.
Special Forces veteran and Bushmaster Firearms founder Mack Gwinn Jr. then acquired the DIP design from Colt, where it was known as the IMP-221. Gwinn Jr. rechambered the design to .223/5.56 so that it could accept standard NATO magazines and ammunition, creating the Bushmaster Arm Pistol. I’d occasionally come across this firearm in gun publications but never in the various gun shops I visited.
The Bushmaster Arm Pistol Today
Though Gwinn Jr. started Bushmaster Firearms with the DIP design, the AR-15’s rise in popularity meant the DIP got lost in the shuffle. The design then nearly disappeared many years later when Bushmaster folded under legal pressure.
Fortunately, Hydra Weaponry has revived the concept and brought the Arm Pistol into the 21st Century with its introduction of the BMP-23. Hydra kept the Arm Pistol true-to-form but as a semi-auto with an updated chambering of 5.56mm
It’s compact, unusual and purpose-built as a survival weapon rather than a front-line battle rifle. Like its predecessor, it remains a niche firearm but one that still sparks curiosity and offers a unique shooting experience.
A Deep Dive into the Hydra Weaponry BMP-23
The Hydra Weaponry BMP-23 sample arrived without an owner’s manual. There also wasn’t one available in the downloadable catalog at the time of writing, but the Hydra representative said one will be available soon. All I had to work with was the product description from the web listing:
“The BMP-23 pistol is a reborn Gwinn Firearms design Bushmaster arm pistol from the early 1970’s. It’s 5.56 caliber with an 11.5″ barrel and AK-47 type gas piston operating system. This lightweight aluminum and steel design weighs in at 5.2 Lbs and has built in iron sights. There’s also a unique 40-degree swivel design for right- and left-hand use.”
Since the above lacked the backstory and insight into the Bushmaster’s role as a survival weapon, I was left to do my own research into how the firearm operated and hopefully find an owner’s manual.
Most reviews I found online, some as recent as 2024, weren’t particularly flattering and often blurred details between the original Bushmaster Arm Pistol and the modern BMP-23.
Tracking down the original Bushmaster directions were helpful, especially in the use of the forward-mounted pistol grip. The unique design of this pistol accommodates both right-and left-hand shooters by tilting (the manual described it as swiveling) the grip.
Though the original manual was immensely helpful, I sought out another perspective from my neighbor, a former member of the special forces. We spent nearly an hour examining the BMP-23 in dry-fire mode.
The pistol comes with rudimentary rear and barrel-mounted front sights, though there is accommodation for mounting an optic. However, neither of us could figure out how to align the rear sight with the front sight. Eventually, I noticed the rear sight could pivot. Once rotated, it finally lined up with the front post to give a usable sight picture. I was finally ready to live fire.
Operating the BMP-23
Though the BMP-23 and previous iterations borrow heavily from the AR-15 operating system, it functions a differently in a few ways. The controls of this pistol reflect that it is a compact survival weapon as opposed to a conventional battle rifle.
- Safety: The safety (and fire control system) is located on the left side of the receiver but cannot be easily rotated with the shooting-hand thumb. The receiver is positioned differently than the original Bushmaster Rifle, so the left hand holds the BMP-23.
- Magazine Release: This sits at the rear of the receiver on the right side and is not as accessible by the index finger as an original AR-15/M16 operating system.
- Charging Handle & Ejection Port: Both are mounted on top of the receiver, allowing the charging handle to be accessed by either hand and easy checks for a clear chamber.
- What’s the Same: The flash hider is the AR-15/M-16 Birdcage suppressor style. Grip is also an AR-15 grip that with the proper base plug that can store small emergency items.
These quirks reinforce the Bushmaster Arm Pistol and now the Hydra Weaponry BMP-23 were meant to be confined-space, last-resort firearms for downed pilots or anyone needing a compact defensive option.
Bushmaster Firearms Arm Pistol/Hydra Weaponry BMP-23 Specifications
*Note: Specs from original Bushmaster instruction sheet
Caliber: 5.56mm/ball ammo recommended
Weight: 5.25 pounds empty
Length: 20.63 inches
Front sights: Post type/tilts with pistol grip position
Rear sight: Adjustable 3-postion V-notch
Barrel length: 11.63 inches
Sight radius: 19 inches
Magazine capacity: 20-/30-round (Hydra 30-round PMag recommended)
Price: $2,350 (current Hydra BMP-23)
The Hydra BMP-23 at the Range
I’ll confess, based on the other reviews of the original Bushmaster Arm Pistol that I read, I wasn’t expecting much when I took the BMP-23 to the range with some 55-grain PMC ammo. Conducting my own live-fire tests reaffirmed that I shouldn’t read others’ reviews before shooting a gun for myself.
I loaded 20 rounds into the PMag, set up a B-27 PROS target and moved back to 25 feet. Holding the BMP-23 in my right hand and the PMag in my left, I tilted the pistol grip to align the rear and front sights.
I sighted carefully on the X-ring of the target and squeezed. The trigger was slightly spongy but easily manageable. The first shot was gentle and pleasant to fire. Better yet, it landed dead in the X-ring! One shot, and I was hooked.
The BMP-23 was fun to shoot and accurate within pistol ranges. I fired four more shots at the center ring. The group measured 3 ½ inches. Another five-shot group to the head measured around 4 inches. A final group of 10 rounds from 25 feet into the scoring box on the top right of the target measured 3 inches.
It was hard for me to see the black-on-black sights on the targets black head, but most of the hits were within the scoring area. I was amazed by the accuracy of the BMP-23 and its manageable trigger. Recoil was light, and empties were ejected well away.
The BMP-23 is also able to be fired from the hip or prone, though that would have been difficult for me with my shoulder damage. A gun with this type of military design lineage and construction can be counted on to keep going.
Hydra BMP-23 Review
The Hydra BMP-23 is more than just a curiosity—it’s a well-executed revival of the Bushmaster Arm Pistol concept. While it isn’t designed as a battle rifle, it shines as a compact survival weapon or specialized defensive tool.
One review I read suggested the BMP-23 would make a great truck gun, but I think it would also excel as originally intended: a compact survival firearm in an aircraft, boat, RV or other vehicle where space is at a premium. It could also make a useful addition to a bug-out bag.
Bottom line: the Hydra Weaponry BMP-23 is a niche firearm, but one that works better than expected. I’d recommend reading up on its history and instruction before buying, but for those intrigued by its history, design and surprising performance, it offers a rare blend of collectability and practical shooting enjoyment.
Hydra Weaponry: HydraWeaponry.com
