The TSW line has enjoyed continuing refinement since first introduced.
Some of the earliest TSW models had the slides and frames matched and numbered during production, but that eventually changed at some point in later production.
Some of the basic changes and improvements over the standard 3rd gen models include ...
Box-type rails instead of the earlier stepped-rails. These are larger, have tighter tolerances and can enhance potential accuracy.
Delayed unlocking, allowing a further reduction in pressure before the barrel unlocks from the slide, which can help lessen felt recoil.
Thicker barrel hoods (and later production models also incorporated the visual loaded chamber inspection port in the barrel tab).
The slides were later machined (after the early 'original' models) to accept the optional spring-loaded, decock-only assembly which returns the decocking levers to the ready-to-fire position after decocking (no 'On-Safe' position). This can be seen when the left side lever is depressed, in front of and under the lower edge of the lever (an additional machined recess and hole located within the recess which serves to anchor the end of a spring on the optional assembly).
There were some minor changes when S&W redesigned their DAO parts to be retrofitted in TDA models (so the same frames and slides could be used regardless of whether the gun was configured for TDA or DAO).
Accessory rails were later added (riveted) to the frame and current production 4006/4566TSW models are available with the option of having the rails machined into the frame itself.
The 'original' compact models (3913/4013/4513TSW's) lacked some of the changes which were introduced in the wider TSW line introduced a bit later, although they did incorporate the box-type rails and delayed unlocking, for example. The early 3913/4513TSW's also had cutaway grip profiles which accepted lesser capacity magazines (1 rd less) than the same compact models subsequently produced.
There have been some continuing changes to the way some of the parts are machined, recoil guide rod designs and some ongoing refinements to the production of many of the standard parts which are shared among the earlier models, both standard & TSW production. Some of the changes and improvements aren't easily visible to the eye unless the pistol is detail-stripped and you know what to look for compared to earlier models.
All things considered, the TSW line is an improvement over the earlier 3rd gen models. I feel they can stand alongside anything produced by Sig Sauer, for example, when it comes to production quality, fit, function, reliability and inherent accuracy.
When I attended a Sig Sauer armorer class we were told that the Short Reset Trigger had been designed to compete against the fast-resetting standard S&W traditional double action trigger in an earlier LE contract bid. While Sig wasn't awarded that contract, they did decide to incorporate the faster resetting (SA) TDA trigger design (new sear & sear spring) in some of their model line.
The TSW line is still being produced and sold to LE agencies (it's in the LE catalog).
During some of the early negotiations between S&W and the CHP there was some discussion of maybe producing 4003TSW's for them using a Scandium aluminum alloy frame, instead of the standard aluminum frame, but they eventually decided to remain with the stainless steel frame model (4006TSW). I was rather hoping they would start offering the Scandium aluminum alloy, myself, and was personally hoping a 3913TSW would be offered with a lightweight Scandium frame.
Didn't happen, though. Scandium aluminum frames are more expensive to produce.
I own a pair of original 4103TSW & 4513TSW pistols. I also carried some current production issued models prior to my retirement. I've always found them to be durable, reliable and accurate pistols which would feed a wide variety of factory ammunition.
I always wanted to add a 3913TSW to my working collection to complement my late production 3913.
The aluminum frame 4003/4563 models are much lighter to carry than the all-steel models, although many folks feel they also have a bit more felt recoil, too. I can say that carrying around an all-steel 4006/4566 is like carrying around a M686 4" revolver all day ... but they do make for enjoyable range guns.
