Originally Posted by BMCM

Haven't personnaly experienced a broken drawbar but I've heard tell of a couple cases where a cracked drawbar was found to be at fault for malfunctions so, I choose to keep spares on hand.
You don't need one for each gun though. Drawbars come in three sizes so I'd say one of each size just in case. small for 9mm single stacks, large for 45xx size guns and fat for the doublestacks. Imagine taking delivery of a new(to you but used) gun and once you get into the guts of her finding the trigger play spring broken off. Well if you have a spare drawbar on hand ready to go you can just swap it out and go for a spin. Fix the broke play spring at your leisure some other time.

Ejectors are common among all the 3rd gens so a couple spares for the entire herd is fine.

Same with sear release levers, common parts across the line only needed if your decock function is out of time. Again a couple spares on hand is plenty.

Extractors are also unique to the caliber. Most likely to be chipped or broken by dropping the slide over a chambered round (bad habit). These extractor are not intended to snap over the case rim, the case rime is meant to slide up the breechface during chambering and under the extractor hook.

If you have a bunch of 9mm guns I'd have a spare extractor or two for the bunch just in case. Like wise if you have a bunch of 45xx, 10xx or 40xx. Have a spare for each flavor.

Cheers
Bill