Walther’s PPQ appears to be it’s most popular offering these days, and the older P99 seems relegated to “also ran” status. For anyone who has owned/shot both, how similar are they in handling and accuracy?
Well nigh identical. I shoot both on a regular basis.
Only noticeable difference is the triggers. (Plus functionality like the decocker and cocked indicator)
But they shoot/handle the same. Same mags, same holster, same sight picture, same excellent accuracy.
If you like glock style triggers, get a PPQ (but IMHO the Q trigger is much better than a glock). Want double action… Get a P99.
From what I have gathered here in research…the PPQ M1 may be the best pistol available today.
I also have owned both, a first gen P99 and a PPQ first edition.
They are basically the same. The PPQ has updated ergonomics and an SAO trigger. The SAO trigger is the same as the P99 trigger when in single action mode.
The P99 has smaller slide levers (like mine did), however you can get the larger slide levers as a factory option on the “Defense Kit” models, which also come with the same night sights as the PPQ FE. Walther hasn’t been importing the Defense Kit model lately though 
In Europe they can get a P99 with the PPQ ergos. Not so here.
I have a S&W 99 in .40 cal. It is almost identical to Walther; in fact the lower says Walther. It is one fine shooting pistol. They stopped production some time ago,; wonder why?
My personal speculation is that it has to do with them (S&W) focusing on developing the M&P which would eventually compete with the P99.
No. It is PPQ, but have “Glock like” (pre-cocked, not SAO) trigger to comply with some regulations on Police pistols (for eg. German “Technishe Richtline”). It is called P99Q to distinguish it from SAO PPQ. It kind of replaces P99QA, but P99QA trigger was much heavier than P99Q. In fact P99Q uses trigger originally intended for P99 RAD Q.
Bottom line: P99Q has PPQ frame, PPQ slide, PPQ barrel and new variant of QA trigger modified for PPQ.
BTW I think most popular P99 variant ever is P99AS - only Polish Police use (if I remember correctly) over 75K P99 in this version.
The P99 is an extremely popular pistol with some subsets of the shooting community. It appears to be one of the pistols that really grabs you, or you’re totally indifferent. Me, I’ve always been in the latter half. I don’t want a trigger system like that. I want a gun that will work the same predictable way every time, without worrying about how I’ve set the trigger to function. IMHO, eliminating that boondoggle is why the PPQ has been so popular while the P99 has never quite made it to “the show”.
Probably a casualty of the Walther/ S&W breakup.
In current production still, however is the Magnum Research MR9. Walther frame, US-made slide. Functionally identical to the P99, I’m told.
http://www.magnumresearch.com/Firearms/Magnum-Research-MR9-Eagle-15-Round-45-Inch-Barrel.asp
The slide is different on the PPQ and the P99Q. The US PPQ does not have the CNC milling cut outs on the rear that the P99Q has.
Due to a QC error, or a manufacturing substitute by Walther. I probably own the only US PPQ with a P99Q slide.
And P99D RAD does not have this slot milled on slide. So what does it prove? Is it P99 or PPQ then? 
And here is product card for P99 D RAD / P99 Q RAD:
http://www.fabrykabroni.pl/img/_114443_karta_produktu_rad.pdf
(first picture is prototype from 2008, that started whole PPQ family, second one is current production pistol).
Since, it does not seem to serve any purpose. I do not know. Actually, I thought it was a design change until someone pointed it out to me on the Walther forum that it came from a P99Q. The P99Q is sold in Europe, but I have a slide from one in the US with PPQ markings. If you know what the extra milling if for let me know. 
Must check with designers at FB Radom if they know. They make slides for “RAD” in Poland so they should know if it has any function.
I haven’t had good luck with my SW99. Has not been a particularly accurate pistol compared to a G22.
Conjecture was the Smith barrels. Recall the SW M&P issues as well
At least the function is solid. I’ll try a little extended range work to see if I can make it better. I’ll probably keep the gun no matter what.
Jarvis makes batches of P99 barrels, probably would work with an SW99. If you want to keep it, might be worth giving them a call to see if they have any in stock.
I really wish they would make a PPQ with a small SS lever.
The all German P99’s are very accurate and reliable.
AFAIK post 2006 production German P99 have … Polish made CHF barrels