P30shtr, the gun was an early production 6906.
I did have to replace some parts along the way, like the extractor, which exhibited some chipping on the hook at about 12K, but hadn't yet started to exhibit any problems. I replaced it anyway because of the chipping. I replaced the recoil & mag springs periodically, and some other minor parts for preventive maintenance (old ejector with a newer, revised one, some springs & plungers, etc).
At one point quite a bit later I decided to replace the slide because of what might have been a machining issue in the extractor recess area after discussing it with the factory. I tried another slide which fit within proper tolerance with the existing barrel on the original frame, and ran that one for many thousand more rounds.
The frame was still serviceable when I finally decided to pull it and take it out of service, although the camming lugs were starting to show a lot of wear. The frames rails were still fine, but then I never shoot the gun dry, either. (I've seen some aluminum alloy frames which experienced some nasty accelerated wear because of insufficient lubrication, too.)
I could probably have safely left the 6906 in service longer, since it was functioning fine and passed all normal bench & live-fire checks, but since it was also my daily duty weapon I decided that it had served its purpose well enough and it was time to replace it with another early production 6906. I ran that one for only several thousand rounds before we started replacing our aging inventory with new guns (TSW's) and I had to turn it in.
I remember when I was talking to a tech at the factory and mentioned how many rounds I'd run through that one 6906. He chuckled and said that back when those early 3rd gen guns were being produced they'd never expected anyone to shoot one that much.
There's another retired cop on a couple of the forums who worked for an agency that used S&W aluminum framed 9's and 115gr +P+ loads for many years. I remember him mentioning that he knew a retired instructor who had run something like 59K rounds of the 115gr +P+ loads through his issued aluminum S&W before retiring and taking the gun with him, and that he was still shooting it (and maintaining it well, apparently).
Naturally, I'd not expect all aluminum guns to demonstrate that sort of service life expectancy. As a matter of fact, I remember returning an original 3913TSW to the factory because of a short crack in the front of the dustcover (which the owner thought was a scratch for the longest time). The gun never exhibited any functioning issues, and it was only discovered because he brought it to me for an inspection and I checked it out under the magnifying lamp. I was surprised when it turned out to a crack and not a scratch, since it was an odd place for it to occur. The factory was puzzled by it, as well, but cheerfully replaced the gun with a new one. As near as the owner could determine, he'd only fired between 12-15K rounds through it (a mix of standard pressure, +P & +P+ loads), and he claimed to have replaced the recoil spring periodically (since I gave him the springs).
Sometimes things just happen.
I have a copy of a report from the late 80's where a fed agency tested a number of the current pistols available for use at that time. The aluminum frames guns of that day could experienced cracked frames as soon as 10K rounds. One of the comments in the report was from one of the gun companies, and it basically said that if LE wanted aluminum framed guns which would exceed the military service life expectancies, that they should request them and not be surprised when guns made to military specs might not last as long as might be desired by LE users. In subsequent years (after that test report) guns from at least a couple of the makers of guns tested made improvements to their models for LE users.
The bottom line to the report was pretty much that steel guns could be expected to last longer than aluminum guns (although slides & barrels were considered replaceable parts over the long term when 80-100K rounds were being fired). No surprise.
How much longer they might last might become a moot point considering how few rounds the actual average private user really shoots, though.
Just my thoughts.
