Across the six videos we've done on Walther's new PDP line the question asked most often is, "which one should I get?". That question is as complex or as simple as you want to make it. All three current offerings (September 2021) offer the same features and overall design. The differences are minor, but do have their own advantages and disadvantages over the other options.
Because the current models of the PDP family of pistols can interchange slides and frames, and all three barrel lengths use the same recoil spring the choices really come down to which barrel length and which grip size. (The lead image is actually the combination of a PPQ M1 frame, limited edition PPQ 5" barrel, and 5" PDP slide) As of the time this was written, factory PDP options consist of a 4", 4.5", and 5" barrel, compact (15 round) or full size (18 round) frames.
Why One Size or Another?
To break it down, take a look at these charts of things to consider if you're trying to pick the best for your needs. That's right, there is no "best" for everyone as we all have our own personal tastes, preferences, and needs. This chart is far from end-all, let us know your take in the comments below.
For the frame the choices are rather simplified as at the time of this article there are two options. Compact or full size. The full size adds three to the magazine capacity, but because the grip is lengthened it changes the feel of the gun in hand much more than a simple +3 magazine extension would.
Personally I've always wanted a 4.5" barreled compact for carry. Magnum Research had a 4.5" MR9 from their collaboration with Walther building a variant of the P99, but I didn't get my hands on one before they were discontinued. I suppose it's a tough size to sell at the gun counter as that combination makes everything else seem more specialized, but to me it's the goldilocks of concealability and portability with plenty of muzzle energy and a nice sight radius. That's possible now, but at the moment requires purchasing a compact PDP and a 4.5" slide. I assume that Walther will eventually make this a factory option as the PDP line fills out.
With the PDP the flare at the bottom of the frame greatly reduces the chances of pinching my pinky with the compact frame that I experiences so many times with the Glock 19. As a result the Walther PDP Compact frame doesn't quite feel like a compact to me and permits the same shooting comfort that other makers need a "full size" frame for. The PDP full-size feels slightly stretched, and although the contours are nearly identical they hit the hand in different spots.
Which is right for you? Only you can truly answer that question. If you were already a fan of the PPQ the PDP offers some of the ergonomic enhancements (which I didn't think were really possible) of the steel-frame line. I prefer the way the compact frame fits my large hands, but maybe that's because I'm so accustomed to being cramped on a pistol that it feels spacious enough. As far as barrel length the 4.5" is my favorite pick as a more-portable alternative to the 5". In the end it really comes down to your personal preferences and intended application.