Two of Walther Arms’ newest PDP variants are the compensated PDP Pro-X pistols. They result from a collaborative effort between Walther and Parker Mountain Machine. These new guns ship with professionally installed Parker Mountain Machine single-port compensators. This is noteworthy because they’re the first factory-compensated Walther PDP catalog items.
Walther PDP Modularity And The Magic Of The Pro-X
From their original conception, Walther Arms designed the PDP family around modularity and interchangeability, especially regarding the core polymer-framed models. PDP-F and steel-frame pistols differ slightly. However, all standard PDPs are designed in such a way that slides, frames, barrels, and recoil spring assemblies (RSAs) can all be combined and still function—even in configurations not available from the factory.
I’ve compared this aspect of Walther modularity in the past to Glock’s releases of the Glock 47 (and later the Glock 49). Their parts were interchangeable with the earlier Glock 45. This allowed end-users to combine compact slides with compact frames (G19), compact slides with full-size grips (G45), full-size slides with compact grips (G49), and so on.
The Walther PDP has this modularity built in. So, dedicated shooters and enthusiasts quickly started mixing, matching, and accessorizing slides with different frames and barrels.
A popular “mod” combines a full-length frame (compact or full-size), a four-inch slide, and a factory-threaded 4.6-inch barrel. Then, install the Parker Mountain Machine compensator over the muzzle. This specific “combo” fits flush inside a full-length frame.
The result is a compensated pistol whose compensator sits flush inside the dust-cover area without protruding over the frame. It’s also the same length as a full-size 5-inch PDP slide and takes up an equal amount of space.
Parker Mountain designed its compensator to conform to the cross-section and contours of the PDP’s slide. So, the unit naturally flows with the rest of the slide and looks smart—not like an awkward, bolted-on afterthought.
An Official Collaboration
With the release of the PDP Pro-X series, Walther took the above concept, collaborated with Parker Mountain Machine, and made it “official.”
Besides being available with either full-size or compact grips, PDP Pro-X pistols also include the standard low-profile Walther aluminum magwell, three 18-round magazines with +2 factory basepads, and the vaunted Walther Dynamic Performance Trigger—the pièce de résistance of the entire PDP family.
The Parker Mountain Machine Compensator
The Parker Mountain Machine device included with the PDP Pro-X is a compact single-port compensator manufactured from 7075-T6 aluminum. It attaches to muzzle threads much like muzzle devices on AR-15s. PMM omits set-screws in its compensators to reduce the liability of their coming undone.
To fasten, these devices use a combination of sheer torque, shims, and red Loctite 272. Once installed, they’re semi-permanent. So, to completely field-strip the pistol, one would have to break the cured Loctite and torque. It’s best to clean around it.
Compensators, like Parker Mountain Machine’s unit, are designed to help the slide track flatter and get back on target quicker. They are not to reduce recoil (though it may feel that way during shooting).
Due to the Parker Mountain compensator’s expansion chamber, it works best with factory loads that are medium-powered or higher. Lighter loads can present a reliability issue because the compensator uses energy from the expanding propellant to function properly.
This means the slide and recoil spring must rely on a smaller share of the cartridge’s total propellant energy to cycle. The PDP Pro-X uses a standard 18-lb Walther PDP RSA (recoil spring assembly), which works fine with standard pressure and duty cartridges. Both Parker Mountain and Walther have lists of recommended ammo brands on their websites for the best results.
The Rest of The PDP Pro-X
Aside from the Walther PDP’s inherent modularity and the Parker Mountain Machine compensator, it would be a disservice to gloss over some of the other key aspects that set the PDP apart from the crowded field of its striker-fired contemporaries.
The Slide & Barrel
Excluding the PDP ACRO Professional variant, which is directly cut for the Aimpoint ACRO footprint, all PDP slides are factory-milled with a generous pocket to accommodate low-sitting optics plates. To supplement mounted optics, all PDP slides use Glock-pattern sight dovetails. This allows them to accept any front or rear sight that fits one of the world’s most popular pistols.
PDP slides have distinctive and easy-to-grab “Super Terrain” serrations fore and aft. Their barrels use a stepped chamber to bolster accuracy. This is a detail that fellow German gunmaker with a penchant for accuracy and reliability, Heckler & Koch, also incorporates into its 9mm pistols.
A stepped chamber has a very slight 0.001-inch constriction that “grabs” the 9mm cartridge so that it sits more concentrically while chambered. PDP barrels forgo traditional rifling and use polygonal rifling instead. In the case of the specific PDP Pro-X factory 4.6-inch barrel, this barrel’s muzzle has ½ x 28-inch threads.
Grip And Frame
The Walther PDP Pro-X’s grip includes all the hallmarks of a modern ergonomic grip. It has an undercut trigger guard with a flat bottom surface, a roomy frontstrap, generous radiusing on the backstrap, and a tapering oval-shaped grip profile. Such a tapering shape allows a solid firing grip with the correct amount of “pinky pressure” towards the magwell area. As a result, it helps to manage recoil.
Backstraps are interchangeable by way of a ⅛-inch roll-pin that also holds the factory aluminum magazine well in place. Finally, the left and right sides of the grip, along with the backstrap, are covered in a moderate tetrahedral texture that Walther refers to as its Performance Duty Texture.
This texturing isn’t aggressive like coarse sandpaper, although it does provide a decent purchase. For extended shooting in hot and sweaty climes, shooting chalk or something with more friction is still recommended.
Dynamic Performance Trigger
I called the Walther Dynamic Performance Trigger the pièce de résistance of this whole pistol—and I stand by that. Before the Parker Mountain device can even compensate for muzzle-climb, the [accurate] shot still needs to be taken, right?
The Dynamic Performance Trigger’s flat aluminum face, crisp break, and reset come very close to emulating a sliding 1911-style trigger. I have experienced it on the PDP Pro-X, the PDP Match SF, and the ACRO Professional. I wouldn’t hesitate to call it one of the best striker-fired triggers currently on the market.
This trigger truly blurs the threshold between striker-triggers and true single-action triggers. On my PDP Pro-X, I measured ten trigger pulls with my electronic trigger-pull scale, which averaged 4 lbs 13.9 ounces. However, due to the crisp break, the Dynamic Performance Trigger on this Pro-X feels “lighter.”
Shooting The Walther PDP Pro-X
I mounted an Aimpoint ACRO P-2 to the PDP Pro-X’s slide using the Walther OEM ACRO plate. I zeroed it with 9mm Fiocchi 115-grain Defense Dynamics JHP and shot a couple of rounds to get familiar with the Pro-X. Then, I immediately loaded some rounds into my “standard” PDP ACRO Professional to feel the difference without the compensator.
Coming into this review, I specifically set the Pro-X up to be otherwise identical to my PDP ACRO Professional. I gave it the same red-dot sight, same trigger, same RSA, and nearly identical barrels so I could focus on the effects of Parker Mountain’s compensator.
The difference was clear, and the Parker Mountain works as advertised. I could easily see the dot returning to target a little sooner while the recoil impulse also shifted by forcing the slide home sooner.
With the non-compensated PDO ACRO Professional, I felt more of a jolt from the slightly more pronounced muzzle-climb. Likewise, I waited a few moments longer for the dot to return to my window and, thus, my target.
50-Round Dot Torture Drill
After the comparison, I fired a 50-round Dot Torture Drill at 7 yards with the remaining Fiocchi Defense Dynamics JHP I had on hand. I scored 46/50 due to carelessness on my end. Dot Torture is a simple drill that I shoot when “getting to know” a new-to-me pistol.
In this instance, I was able to observe how the dot tracked slowly. If I’m honest, two of those dropped shots came from a sense of confidence trying to shoot more quickly due to how the pistol actually handles.
Slow and deliberate shooting isn’t an end-all-be-all in evaluating a pistol. However, an exercise like Dot Torture is a great ice-breaker. This is also why I like to bring review guns to USPSA matches. It allows me to shoot pistols in a more spirited and aggressive manner. And that’s exactly what I did with the Walther PDP Pro-X.
Due to the Parker Mountain Machine Compensator, the only valid USPSA division for the Pro-X is “Open Minor,” without exceptions.
I shot 124-grain Speer Lawman during my match. It is a tried-and-true training load and one recommended by Parker Mountain Machine. I had 0 issues between the six different stages, and the pistol ran wonderfully. I was once again grateful for the Dynamic Performance Trigger. It served as my guardian angel, making it possible to take clean, long-distance A-zone shots across stages with confidence.
I shot another match the week after, using a lighter recoil spring and 115-grain Blazer ammunition. I had no issues, but I think the pistol returns to zero better with the heavier and standard RSA.
The Takeaway
The only “issues” I experienced with the PDP X-Pro were self-induced while shooting Dot Torture Targets #5 and #8 (single-hand only). These failures to eject happened specifically due to my very loose grip. Trying to hold a pistol still and shoot a 2-inch circle at 7 yards, one-handed only, can be challenging.
I have no doubt a firmer grip (or a lighter spring) would have cycled the slide. At the time of this writing, the pistol has seen approximately 500 rounds without major issues other than those described above.
Shooting the uncompensated PDP ACRO Professional next to the PDP Pro-X was very valuable for the insight and clear differences between both pistols.
However, no compensator on any standard 9mm pistol, including Parker Mountain’s, can magically turn said pistol into an open-division racegun. There are too many engineering and reliability challenges, not to mention the limitations of the 9mm Luger cartridge itself.
Including a compensator like Parker Mountain’s can help a pistol bleed off a bit of “felt recoil” and, more importantly, return the sights/dot to target that much quicker for faster splits. When this capability is paired with a pistol like the Walther PDP Pro-X and its easy-shooting Dynamic Performance Trigger and optics-ready slide, sparks will fly.
For more information, please visit WaltherArms.com.
Walther PDP Pro-X PMM Specs
| Caliber | 9mm Luger |
| Action | Striker-Fired Semi-Automatic |
| Frame Material | Polymer |
| Slide Material | Steel |
| Barrel Length | 4.6 inches |
| Overall Length | 8.5 inches |
| Height | 5.7 inches |
| Width | 1.4 inches |
| Weight | 24 ounces |
| Trigger | Walther Dynamic Performance Trigger |
| Magazine Capacity | 20+1 |
| Magazines Included | 3 |
| Optics Ready | Yes |
| MSRP | $999 |
Performance
| Federal Premium 124-gr HST JHP | |
| Muzzle Velocity, Std Dev, ES | 1164.5, FPS 16.7, StDev 58.5, ES |
| Min Group (inches) | 1.0 |
| Avg Group: | 1.58 |
| Max Group: | 2.25 |
| Staccato Range 124-gr FMJ | |
| Muzzle Velocity, Std Dev, ES | 1186.9, FPS 6.7, StDev 30.8, ES |
| Min Group (inches) | 1.00 |
| Avg Group: | 1.43 |
| Max Group: | 1.88 |
| Nosler ASP 124-gr JHP | |
| Muzzle Velocity, Std Dev, ES | 1162.3, FPS 12.1, StDev 50.7, ES |
| Min Group (inches) | 1.75 |
| Avg Group: | 2.63 |
| Max Group: | 3.50 |
| Hornady Critical Duty 124-gr +P | |
| Muzzle Velocity, Std Dev, ES | 1211.1, FPS 10.7, StDev 47.0, ES |
| Min Group (inches) | 1.75 |
| Avg Group: | 2.31 |
| Max Group: | 2.63 |
