Okay, here's the gist of what I sent in the PM.
While I can't diagnose what's happening with your particular 1006, if it were happening to one being used on our range, I'd suspect one, or a combination, of the following things ... (presuming a reasonably clean pistol).
Chipped/broken extractor hook.
Dirty/fouled extractor recess under extractor.
Aging/weakened extractor spring.
I've been replacing an increasing number of extractor springs in our issued S&W pistols in recent months, but then most of our aging inventory is going on 15 years old, and that's not unusual for extractor springs to start exhibiting weakening by that age ... especially when you factor in pistols which may have seen a fair amount of use.
If the extractor spring is just getting to be old enough that it's becoming weakened to the point that it provides less than proper tension against the tail of the extractor, then you might expect to start seeing some failures-to-extract, caused by extractor's hook simply being bounced out & around the case rim during recoil. The extractor spring has to be strong enough to tension the tail of the extractor outward, and therefore the hook inward, during the initial part of the recoil forces being experienced by the pistol (this is often called 'moment of mass', FWIW).
The factory recommended specification for 10mm (and .40 S&W) pistol extractor tension is 4-8 lbs, and it's measured with a dial gauge. The reason there's a 'range' is that occasionally some pistols might experience optimal functioning within different portions of that range. It might also permit a factory technician, gunsmith or armorer to 'adjust' the amount of extractor spring tension in order to provide for best functioning when it comes to any particular ammunition preferences, too. The tension is 'adjusted' by the use of different springs (of varying rated strengths). The variable factors involved in ammunition production & quality control can lend themselves to some interesting circumstances, especially when it comes to pressure levels and case rim dimensions. A weakening extractor spring potentially might become more noticable when using different ammunition. So too, might a chamber which becomes 'stickier' with fouling more from one type of ammunition, than perhaps with another.
It's also not uncommon to find that in pistols which have been used for a long period of time, such as approaching 10 years or so, that the extractors have started to become 'work hardened', and this may manifest as chipping ... or outright breakage of the hook. In addition to the spring strength, I always examine the extractor when a pistol starts to exhibit weakened extractor spring tension. Sometimes I find the extractor has started to exhibit some chipping. When that happens, I not only replace the spring & the extractor, but also the ejector (which has been working as hard to kick the cases free as the extractor & spring have been working to extract & hold the cases).
S&W extractors must be 'fitted' to each pistol's slide. They are NOT intended to be considered 'drop in' parts. Fitting them involves filing on the extractor's adjustment surface (the flat surface behind the extractor's hook, which engages the inside of the slide's extractor slot recess), and the use of bar & flag gauges to check some 'fitting' dimensions. While the dial gauge checks the spring’s tension (once the extractor has been properly fitted), the bar & flag gauges are used to check a couple of critical dimensions of the hook's positioning. These dimensions involve the positioning of the extractor's hook in relation to the opposite shoulder of the breech face, as well as the dimension between the 'inside' surface of the hook and the breech face immediately behind it. It should be done by a gunsmith familiar with S&W pistols, or the factory (or a L/E armorer, if you know one). The factory might be the best bet, and would be what I’d recommend (unless you locate a gunsmith), since sometimes (especially on the earlier '3rd generation' production pistols) it might require trying a couple or more of the different available extractor springs before one is found which offers optimal functioning in any particular pistol. Then, there's always the occasional pistol where the 'right' spring tension might even be outside the 'recommended' tension range. After all, the final proof is in the actual functioning when it's being fired, and not just when being inspected using 'bench checks'.
While you’re at it, I’d also replace the recoil & magazine springs, especially if you don’t know their age. S&W recommends that both of these types of springs be replaced every 5,000 rounds, or every 5 years, whichever occurs first. This is a conservative recommendation, and is probably erring on the side of safety for liability reasons. (We're talking about defensive weapons, after all, when it comes to L/E and personally owned pistols which may be used for defensive purposes.)
By the way, I'm flattered that you mentioned me in relation to Tuner, but you need to understand that I'm NOT a gunsmith ... and I'm certainly NOT an 'expert' anything ... but only a factory trained L/E armorer. This places me more in the realm of a simple 'Plug 'n Play' parts replacement kind of guy.
Call S&W, and they can get your 1006 back up and running the way it was intended and produced way back when ...
It would also give them a chance to give your pistol the 'once over' to see if anything else might benefit from any newer production/upgraded/revised parts, as well. Nice folks.
Best,
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