I became interested in the SW99's after attending my (first) SW99/P99 armorer class. I ordered one of the standard size SW9940's.
I carried an issued SW9940 for a few years, too, and as an armorer I helped support a small number of them (50, plus some owner by other instructors and shooters). I've fired a few ten's of thousands of rounds through them (since the agency was supplying the ammo most of the time
).
Once S&W engineers helped Walther diagnose an "early slide stop" issue that had been reported in the early P99 .40 and SW9940's, and Mec-Gar redesigned the magazine body (at the slide stop notch cutout) and the follower, it seemed like a pretty nice and reliable model line.
I ordered a compact version SW999C after another armorer class. It experienced an occasional light-strike issue in DA (only, not in SA). I discussed it with the smith for S&W's Walther America company, who told me he'd seen the same thing in some P99's, and told me how to change the height of the trigger bar guide post to correct the issue. Once that was done, I put many thousands more rounds through the little Compact. Neat 3.5"/10+1 9mm pistol.
For the sake of trivia, in the Anti-Stress (DA/SA) 99's there's a "timing" that has to be achieved and balanced between the DA and SA striker travel and safety block engagement. The trigger bar guide controls the release of the striker by the trigger bar, and the dimension of the trigger bar guide post is critical to achieving this "timing". There are some different dimension (height) guide posts available to achieve the correct timing of the trigger bar's release of the striker. In later 99 models, and then the PPQ, the trigger bar guide post was changed to an adjustable lever design (which required a change of the frame and sear housing block dimensions). The new lever could be adjusted via a screw, versus replacing the guide post with another one. I was told the PPQ required no adjustment, since it's a single action only gun and doesn't have to deal with the "timing" of both a SA and DA trigger pull/striker release.
I eventually went through a 3rd armorer class for the SW99/990L guns. Personally, I never cared for the 990L's (think P99 QA, but without the field-strip button to decock the striker), and much preferred the AS version. Still do.
My compact SW999C is such a sweet handling small gun, with such a great trigger in
both DA & SA, that it usually allows me to easily produce tighter groups, faster, than when using my 3913, 3913TSW or G26. (And I like all of those other guns a LOT.)
As an armorer it's not as simple as the Glock, and in some ways a bit easier to work on than a M&P.
I liked that the 99's extractor and striker assemblies could be removed independently of each other (for cleaning), but the extractor removal & installation involving the removal of 2 different plungers (safety block and the actual extractor plunger) could require some attention on the part of an armorer.
I've posted a fair bit of my experiences and opinions regarding the SW99's in other threads, and I don't have the time to revisit it all here.
Suffice to say the SW99 and P99 in AS configuration remain a couple of my all-time favorite plastic pistol lines. Very under appreciated for what they offered.
FWIW, someone from the S&W factory told me during an armorer class that the frame and all the frame parts/assemblies, and all the slide parts aside from the bare slide and barrel (both made by S&W), were provided by Walther and assembled by S&W.
There were some minor differences in how S&W wanted the frames molded. S&W through-hardened heat treated their slides and barrels, while we were told Walther used the traditional European method of zone-tempering at high stress spots. Both companies used different trademarked versions of nitrocarburizing surface hardening methods (Tenifer v. Melonite).
Also, S&W decided to use the optional extractor spring (heavier) in the SW99's at some point, and in all the 990L's ... which was also the same spring used for the mag catch assembly. Initially we were told that if we encountered any extractor/ejection issues, to simply replace the standard extractor spring with the optional one.
Oddly enough, it was when one of our people brought in a P99 with extraction issues that I first used the heavier spring. I called S&W to confirm the same optional extractor spring could be used in the P99's, and resolved the owner's problem by replacing the original spring with the optional heavier one. Then, I had the same thing happen with another cop's personally-owned SW999 (full-size 9). I replaced the original (9mm) extractor spring with the optional heavier spring, and everything ran fine. I think Walther later listed the heavier spring as a standard .40 extractor spring, but I'd have to dig through one of the later armorer manuals (from Walther) to see if I'm remembering it right.
Great guns, though. Without meaning to step on anyone's toes, I was a bit disappointed when I was using a T&E SW9945. It just didn't have the same feel as the slightly smaller SW99's. I didn't buy one of those (but I bought a M&P 45 in '08, when they were available for armorer purchase).
