Tested: Heizer PKO-45 Pistol

posted on October 8, 2018

Starting a new gun company in the United States is no mean feat these days. After working its way through all of the regulatory red tape, assembling the right equipment and a team of specialists in a workable facility, the company then has that one, all-important, make-it-or-break-it manufacturing decision to make: Will the company build guns based on time-honored designs or take the product lines in new directions?

Heizer Defense, still a relatively young gun maker, is by no means a garage operation. The company's principles, including Charles K. Heizer (founder, president, and CEO of Heizer Aerospace), Thomas Heizer and Hedy Jane Heizer-Gahn, all hold degrees in mechanical engineering with more than a century of combined experience in working with design technology and manufacturing in the commercial and military branches of the aerospace industry. They also happen to be avid shooting sports enthusiasts, with a strong desire to preserve the second Amendment and contribute to the diversity of firearms the U.S. market has to offer. 

In 2014, the company opted to make a splashy entrance into the shooting market with the announcement of the all-stainless steel PS1 "Pocket Shotgun," a single-shot, break-action .45 Colt/.410 derringer. The PS1 was soon followed by two unprecedented rifle-caliber pocket pistols, the PAR chambered in .223 Rem. and the PAK in 7.62x39 mm, both of which are available with progressively ported barrels to manage felt recoil. Heizer Defense then moved into the concealed-carry semi-automatic pistol market in 2016 with the announcement of the PKO-45 chambered in the venerable .45 ACP, which has become one of the company's most popular offerings. Here is a closer look at this unique pocketable pistol.

The PKO-45 pistol is an internal hammer, blowback operated single action. It will most likely catch the shooting enthusiast's eye because of its unique profile, but once the pistol is in hand, the slim profile and high-quality craftsmanship are what make it stand out from the crowd. The pistol’s aerospace heritage is clearly evident throughout in the clean lines and tight fit of the components. The slide, trigger and other controls were smooth right out of the box before adding any lubrication.

The pistol is constructed almost wholly of machined 17-4 aerospace-grade stainless steel which has been heat treated using a proprietary process. The trigger and grip safety are milled 7075 aluminum with a hard-coat anodized finish. No MIM parts are used, and the only polymer to be found in this pistol is the sight system fiber optics and magazine baseplates. The metallic 3-dot sights are dovetailed into the slide with a single green fiber optic in the front and a pair of red light pipes at the rear. The rear sight has a set screw which can be loosened to allow it to be drifted for windage. The slide and the fixed barrel have both been given a matte-black PVD (Physical Vapor Deposition) finish for added durability, lubricity and a handsome two-tone appearance.

It's not uncommon for fixed-barrel pistols to have a single, round wire recoil spring placed over the barrel, using the barrel itself as the action's guide rod. The slide then fits over the barrel and spring. The PKO-45, however, uses a completely different design. The slide contains a recoil assembly that rests directly on top of the squared-off barrel, resulting in a lower bore axis. This in turn contributes to a reduced level of muzzle flip and a straight-back movement of the pistol during recoil.

The muzzle of the pistol is beveled for easy reholstering, as are the top edges of the slide. The rear of the slide is serrated and indented on both sides. These 2" long indentations slim the slide in that area down to just 0.6" with distinctive raised edges around them. The result is one of the most secure gripping surfaces for cocking a pistol that I've worked with.

The takedown lever, located on the left side of the slide directly below the front sight, allows the pistol to be field stripped for maintenance without touching the trigger. After removing the magazine and verifying the pistol is completely unloaded, hold the PKO-45's slide with a fingertip over the recoil plug while rotating the takedown pin up from the 3 o'clock to the 12 o'clock position, and then pull it from the frame. Remove the takedown pin. Remove the recoil plug and single recoil spring through the front end of the slide and then press the slide backward off of the frame. The pistol is now ready to clean.

Removing the slide exposes a pipe-shaped recoil spring housing mounted directly to the top of the square-profile fixed 2.75" barrel. The sides of the barrel have been deeply grooved to reduce weight. A look through the field-stripped barrel reveals traditional 6-groove rifling and a well-polished feed ramp. A pair of internal 1.70" slide rails are located at the back end of the slide below the rear sight. The slide cover is also grooved to provide a slight extension to the rails.

The stainless-steel frame is a clamshell design with an integrated dust cover, trigger guard and grip frame. All of the edges have been neatly rounded off for a sleek look and a smooth feel.  The shells are secured to each other using five hex-head retention screws. The folks at Heizer Defense pointed out that these screws should not be removed or the frame dismantled for any reason. If you run into a problem that cannot be resolved by field stripping the pistol, it should be returned to Heizer for evaluation and repair. 

The dust cover is milled with a proprietary 0.7" accessory rail for laser and light modules which are, at the time of this writing, still in development. The squared-off trigger guard houses a smooth-faced, single-action aluminum trigger which on this particular gun exhibited just a hint of take-up before breaking cleanly with 5 lbs. 3 oz. of trigger pull.

The external controls consist of an ambidextrous thumb safety, a left-side mounted slide catch lever, a left-side round button magazine release and a trigger-like grip safety located along the front of the grip, just below the magazine release. When engaged, the thumb safety locks up the sear while the grip safety prevents the trigger from cycling until the pistol is properly gripped by the shooting hand. The slide catch does lock the slide open when the last round is fired. A visual and tactile loaded chamber indicator is located on the right side of the slide. An internal loaded chamber disconnect prevents the pistol from firing if a chambered cartridge is not properly seated in the chamber. There is no magazine disconnect, which means the pistol will fire when the magazine is removed from the grip.

The PKO-45's slim, two-finger grip's profile has been borrowed from the company's single-shot derringers. The texturing of the fixed grip consists of the Heizer logo and curved grooves engraved directly into the steel of the frame. The pistol ships with a pair of proprietary stainless-steel single-stack magazines, including a flush fit 5-round model along with a polymer sleeved 7-round magazine, which acts as a grip extension.

The all-steel construction gives this pistol an unloaded weight of 28.8 oz. with an unloaded 5-round magazine inserted in the grip. That makes it nearly 6 oz. heavier than a Glock G36 single stack chambered in .45 ACP. However, the PKO-45 is an inch shorter in length, 0.2" narrower and has the durability that comes with a steel frame.

As a fixed-barrel, blowback operated, sub-compact chambered in .45 ACP with an exceptionally slim grip profile, one might reasonably expect this gun to produce a potentially uncomfortable level of felt recoil. However, thanks to its thoughtful engineering, the PKO-45 generates moderate levels of recoil that keep it manageable even when firing +P loads. Heizer recommends that those who choose to feed this gun a regular diet of +P ammunition replace the recoil spring after firing 4,000 rounds, instead of the 5,000 rounds recommended when the majority of ammunition fired operates at standard pressure levels.

The PKO-45 experienced two failures to feed in the first 20 rounds, but it was smooth sailing after that. There were no other malfunctions related to the gun, ammunition or magazines. The magazines do drop free when released. However, due to the short grip, the little finger has to be moved out of the way for unloading and reloading. The trigger pull is similar to that of the 1911, with a short stroke that moves straight back. The fiber-optic sights are low profile for a no-snag draw, but large enough to be useful and quick to acquire. Formal bench rested accuracy testing was conducted at 7 yards by firing five 5-shot groups for each load.

Formal bench-rested accuracy testing was conducted at 7 yards by firing five 5-shot groups for each load with velocity checked for 10 rounds using a Lab Radar chronograph. Barnes TAC-XP 185-gr. +P jacketed hollow point launched with 796 f.p.s. of muzzle velocity for a muzzle energy of 260 ft.-lbs. It printed a best single group of 2.63" with a five group average of 2.89". Black Hills Ammunition 230-gr. jacketed hollow point averaged 732 f.p.s. for 274 ft.-lbs. of energy. Its best single group was 2.16" with an average of 2.45". Hornady American Gunner 185-gr. XTP jacketed hollow point yielded the tightest single group of 2.06" with the best average of 2.18". Bullet velocity averaged 772 f.p.s. for a muzzle energy of 245 ft.-lbs.

When I first picked up the Heizer Defense PKO-45, with its super-slim profile and sci-fi blaster appearance, I didn’t know what to expect. Folks who have followed my reviews over the years know that I enjoy working with outside-the-box firearm designs, but this one seemed fairly far out even for me. Once I pulled the trigger however, all of the pistol’s unusual features came together for an unexpectedly positive shooting experience. Its uncommon recoil assembly placement, over the barrel instead of under it, provides a low bore axis which contributes to moderate levels of felt recoil despite the .45 ACP chambering. The sights are useful, the grip is comfortable and the trigger smooth and easy to work with.

Some folks will be quick to dismiss this model because of its unusual appear and configuration (the Rhino revolver and Gen1 Glock pistol received a similar reception). Nevertheless, this packable pistol has plenty to offer those who are willing to try something new.

Manufacturer: Heizer Defense
Model: PKO-45
Action: Blowback-Operated Single-Action Semi-Automatic
Caliber: .45 ACP
Frame: 17-4 Stainless Steel, Clam Shell Design
Slide: 17-4 Stainless Steel 
Barrel: Fixed, 17-4 Stainless Steel  
Removable Grips: None
Sights: Fiber Optic, Dovetailed Metallic Housings
Trigger: 7075 Aluminum, Hard-Coat Anodized
Trigger Pull: 5 lbs. 3 oz. (As Tested)
Grip Safety: Front Mounted, 7075 Aluminum, Hard-Coat Anodized 
Manual Safety: Ambidextrous
Loaded Chamber Indicator: Yes
Loaded Chamber Disconnect: Yes
Magazine Disconnect: No
Accessory Rail: Proprietary
Barrel Length: 2.75"
Overall Length: 6.20"
Height: 4.75" with 5-Round Magazine
Slide Width: 0.80"
Grip Width: 0.80"
Weight: 28.8 oz. with Empty 5-Round Magazine
Capacity:  5+1 or 7+1 Rounds
Twist: 1:8” RH
Rifle Grooves:  6
Accessories: Zippered Soft Case, One 5-Round Magazine, One 7-Round Magazine, Replacement Light Pipe for Sights, Lock, Owner's Manual
MSRP: $899





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