Since my dept was the one responsible for the development of the BPLE I can say I've run quite a bit of it. When we issued the BPLE I and all the Troops ran thousands of rounds thru 2nd and 3rd gen S&W autos every year. Normal dept order was about 7 million rds a year. During the time we were issued the BPLE our issued guns were the 439, 469, 5904 and 6904.
After the BPLE we went to the W-W 115 +P+. Not a lot of difference between the 2. Not long after going to the W-W rd one of our range officers was told by an officer in another agency that our 5904s would not stand up to the W-W +P+ rd. Our range officer took that as a challenge. He documented every rd fired thru his 5904 and he only fired the W-W +P+. At around 50,000 rds he noticed the accuracy was starting to worsen. His barrel was getting shot out so he replaced. He did replace the springs are regular interval but I don't recall at what round count he replaced springs. When he retired he had documented 80,000 rds thru his issued 5904. He bought that gun when he retired and when I saw him a couple of months ago he was still shooting it. He retired about 20 years ago and has been shooting that same gun since retirement.
This is not saying your 3913 or any other alloy S&W will go 80,000+ rds. His gun might have just been a particularly good one. It was his issued gun so he might have just gotten the luck of the draw when his was issued. But at least 1 gun I know of that has a documented round count and is still running.
Personally I ran many thousands of rds of BPLE thru my 459 when I was one SWAT. I ran on average at least 50 rds a week thru it of the BPLE for several years. I still have the 459 and it's a great shooter. Other than blue wear it doesn't show any peening or indications of high pressure wear.