So if the spring is painted yellow then we have the updated version?
Depends.
All that might be said (without actually examining the rest of the gun) is that the yellow slide stop assembly spring, if present, is the latest revision. The original wire spring was unpainted, and then it was followed by a red one, and then a light blue one, and then the yellow one.
The red one remained in the 9's when the .40's & .45's received the light blue one, and then the yellow one came about during some further testing of the .357's, and then was selectively used for repair purpose in some .40's. Now it appears they're going to standardize on the yellow spring in all the standard models.
The original slide stop assembly with the yellow painted wire spring was being used before the slide stop assembly was
itself recently revised to add the angled bend on the right/rear bottom corner. I replaced a slide stop assembly with the yellow spring in one of my M&P's with the new revised slide stop assembly with not only the yellow spring, but also with the new beveled corner on the right side lever.
Now, for everyone else who is eager to have a noticeably tactile "reset" ...
All this talk of trying to discover the absolute latest & greatest revisions (plural) in any particular production vintage of M&P's is all fine and dandy, but I've been handling and shooting random models made over the last several years, including some pretty recent ones (and including a M&P VTTC 9) ... as well as some that have had the popular aftermarket parts added to them (by armorers) ... and I've listened to other instructors & armorers express their opinions that they've all started to feel pretty much alike when you stand around on the firing line trying the triggers in both dry & live-fire. Especially in dynamic live-fire drills, when you aren't standing around carefully listening and feeling for "tactile trigger reset".
The whole "sear reset issue" may be popular on the internet, and to slow-fire target/competition shooters ... and the market demand for such a feature has prompted S&W to try and meet the perceived desire for this feature ... but shooting to trigger
recovery in dynamic, past-paced & demanding training & qual drills seems to be something you hear discussed more often by LE firearms instructors, compared to trigger
reset.
I've seen at least my fair share of folks try to keep their fingers on the triggers of their pistols after firing an intentional shot (or shots), trying to hold them at the "reset point", and then experience their guns unexpectedly firing. Sometimes it's seemed it was them unconsciously rocking the triggers during recoil ... or being startled (which having the weapon unexpectedly discharge can
really do to someone, yet further lending itself to another "startle response") ... or experiencing a muscle tremor (yip, etc).
Losing balance momentarily (balance destabilization was the popular term for a while), or hand/finger confusion (mixing up tasks being done by one hand with the other) may also be factors. I've known a couple of highly trained and experienced LE folks end up putting holes in things they didn't intend to shoot when their "trigger fingers" mirrored what their other index fingers were being told to do, performing other tasks in high stress situations.
It's just that if the gun fires without the shooter having made a conscious decision to fire that specific round, the round is still going to land somewhere, and the shooter is still going to be responsible for it ... and being in the position of saying that their finger had been deliberately on the trigger, trying to hold the trigger at the "reset point" when the weapon discharged, isn't something anyone probably wants to try to explain. Especially in a legal proceeding.
Hey, just some thoughts. Sorry for going off-topic, but I sometimes feel this whole "trigger reset" thing is often blown out of proportion and taken out of context by some folks.
