Age really isnt the issue here, its use. Other than maybe lack of maintenance/care, abuse, etc, the gun isnt wearing out if it isnt being shot.
10K rounds over 10 years, is only 1K rounds a year. Basically less than a 100 rounds a month. Not exactly "high volume" wear and tear.
From 2009 to 2019, I shot the same Glock 17 in weekly practice. 300 rounds a week minimum, and often more. In those 10 years or so, I had three things break on the gun. A trigger return spring at 90K, another one at 120K, and a rail in the frame went at right around 150K.
At that point, I sent the gun back to Glock, and they replaced the frame, even though it was 9 years out of warranty and I had stippled the frame, and they rebuilt the rest of the gun as well, and didnt charge me a dime. Im still using it as my practice gun and shooting it at least once a week today.
During that time, I was carrying another 17 as my daily carry, and shooting that gun at least once a month or so. That gun is a Gen 3 RTF2 "Gilly", and a couple of years back, seeing that those guns have become somewhat more desirable (Ill hold short of "collectible"
) I swapped it out for another 17, a Gen 4 that Id picked up at some point, and Ive been carrying and shooting it since.
The great thing about having multiples of the same gun is, you have options and you dont have to worry about carrying a higher round count gun (whatever that may be to you) and having something go at a bad moment, or even just go in practice.
Youll also have a pretty good idea from your practice gun, when things might could start being a problem and when you might run into problems. I would think for most of the better, big name guns with decent reps, that's going to be a ways down the line too, but you never know. Things do happen. And no matter when that might happen, or if youre unfortunate enough to actually have to use it and lose it to the authorities, you'll have an exact duplicate you can pop right back in your holster and carry on.
At this point, with things like Glock, SIG, HK, I wouldn't really have a problem taking a gun from the box, load the mags and pop it in my holster. I still wouldn't do that, and would still vet anything I was going to carry, but from past experience with those makes, it would not have been an issue. Nor would putting a lot of rounds through them bother me either. If youre going to be picking up duplicates down the road, it only makes sense to me, to rotate the older, more used things out into other roles, as the newer stuff comes in.