You folks either shoot ALOT more than I do......or you're beating on those pistols, to need so many parts.
Extra sideplates? Are getting the grips on and off causing that? Seriously, what parts are you seeing break? Regards 18DAI
Edited to add: Fastbolt, what parts does the armorers manual suggest you keep on hand? For how many pistols?
Hey, how 'ya doing?
You're right, unless you're supporting a few hundred 3rd gen guns, or do a LOT of shooting, you probably don't have to stockpile a lot of parts.
Going back to my first 3rd gen pistol class, they suggested that if a few hundred guns were being used (we were running 450+, as I recall), a reasonable number of spare parts might include:
(12) each of decocking system plungers & springs (mostly because they get lost at the bench during inspections

)
(12) each trigger play springs & rivets (I'd double up on the rivets, myself)
Then, maybe a few extras each of ...
Ambi levers (lost

); extractors (incl springs & pins); mainsprings & caps; lever springs (which can REALLY get lost at bench

); ejectors; sear release levers; mag catch springs, nuts & plungers; sideplates; drawbar springs & plungers; mag safety plungers (nylon); plunger springs for the mag safety & firing pin safety (because they can easily get mangled or clipped during rear sight base installation by an inattentive armorer).
Some extra recoil & mag springs for an occasional damaged spring (and then periodic replacements of both, but that can run up in cost pretty quickly when you're talking about a lot of guns).
It took several years for us to eventually exhaust a relatively modest supply of our original spare/repair parts. (We're talking a frugal supply.)
While a couple or so older drawbars cracked (2-3?), or an odd sear release lever might wear down (again, 2-3 guns?), it wasn't until the guns had been in-service (and abused) for around 12-16+ years that we started to see several extractors & ejectors start to require replacement (chipped/broken extractors, weakened extractor springs & broken original-style ejector tips). I've not had a newer/revised style ejector yet break, myself.
One guy from the factory once said that a thumbnail guesstimate might be that extractors & their springs were probably good for at least 10K rounds or 10 years of service use (and abuse). My first chipped extractor in one of my issued guns occurred after I'd fired a little over 12K rounds through it, and I wasn't the first person to whom it had been issued.
Aside from a very few broken extractors that coincidentally were used by guys who couldn't understand that the ammo should be fed into the chamber from a magazine,
not by hand, like I mentioned, we didn't see much in the way of extractors having to be replaced until the guns had been in-service for many years.
I've seen one bent (yep, bent) firing pin, a few shortened firing pin springs and a couple of peened firing pin safety plungers, a couple of mangled nylon ejector depressor (mag safety) plungers ... one of which was from a broken ejector not recognized by the private owner ... and a very few worn hammers & drawbars.
The steel mag butt catch plates might rarely have a post break off (I've seen ONE), and the plastic ones (assorted models and production periods) might get worn.
Followers can get worn. Mostly the .45 followers which have a thinner plastic wall/shelf under the slide stop lever's tab, and that little raised bump on the top (to help prevent the last round from being displaced under recoil).
The old-style guide rods need to be checked for the collar staking coming loose. Once the staking becomes loose and you can easily turn the collar within the rod body, it's time for a new rod. (If & when it becomes looser, the rod can separate from the collar.)
Ditto the side plate, in that if the staked pin becomes loose and it can be easily turned within the plate (removed from the frame), it's time for another plate.
I've seen more instances of sideplates being damaged from improper grip removal & installtion, though, or sideplate removal/installation, where the legs of the side plate (which snap over the left end/head of the sear pin) become tweaked, bent or broken. The sideplate legs are important to anchor the sideplate so the small front angled plate can properly engage the slide stop lever plunger. A loose sideplate can let the angle of the little plate shift under the slide stop lever plunger, and this can create functioning issues (like "early slide stop", or having the plunger slip off the plate, get trapped, etc).
The older style drawbars had some sharper angles which might eventually develop a stress riser (and crack). Even the odd (seldom) new one, however, might require some careful fitting (filing) of the radius under the drawbar head so it reaches around the trigger pin and gets its tail back far enough under the hammer notches. When I say seldom, I mean the filing is discussed ... but not practiced ... in the armorer class. I've only ever had to do it to ONE pistol (3913TSW), myself, and that's out of more than a thousand 3rd gen guns I've helped support (and none of the other armorers with whom I've worked have ever had to do it).
Speaking of drawbars, though, they're the most expensive frame assembly, and I like to have 1-2 spares for the different model/calibers ... just in case ... and I haven't needed to replace one for several years.
Since they no longer teach armorers to repair or adjust slide stop lever assemblies (whack with a babbitt to adjust the pin & body angle, and/or replace a plunger, spring or itty bitty roll pin), it might be helpful to keep a spare slide stop assembly on hand. We were originally told to watch for signs of increased recoil forces (9mm +P & +P+ duty ammo) resulting in the slide stop lever assemblies acquiring an increasing "bend", meaning either an inward or outward angle relationship of the lever body & the cross pin - versus the original 90-degree angle). Recoil forces can do funny things over time in some guns. I've actually had to replace a few slide stop lever assemblies in newer .40 & .45 TSW's for tolerance/fit/function issues. Just a handful out of a few hundred guns. I consider the 2-3 of each of them I've put back (for the single/double column frames & calibers) to be a lifetime supply for both my own guns, as well as those of a couple of friends & relatives who own & shoot 3rd gen guns.
I've had to replace a few mag catch bodies and nuts. A slight tolerance/fit issue in a couple of newer guns, and then a few rusted/corroded springs in older guns.
I shoot a fair amount, BTW. (Hey, the ammo as an instructor & armorer is the right price.

)
Aside from mag & recoil springs being replaced periodically, my personal collection of spare/repair parts mostly sits in drawers & bins while my guns get used.
Sorry if this info is rambling or without organization, but I was just using a simple list from my old notes and adding some observations I could think of off the top of my head.
Now, for folks who like to think they've seen enough video clips or bootlegged armorer manuals to make them qualified to start repairing, modifying or "improving" their own pistols? Well, perhaps S&W would have to really increase their parts inventory in order to keep the gunsmiths, repair techs and armorers in enough parts to correct things.
Best.