Beretta has a bunch of guns that are distinct, but not very different. i.e. the 680 family: 682-old, 682-new, 682-newest, 686 & 7, the later in a host of grades and configurations, some of which are competition guns and some are hunting.
Then Beretta has the Sidelock competition guns: the SO series - both ferocious and beautiful, and the DT-10, a good-but-weirdly unpopular competition gun.
Perazzi has made 200 models, each with a different combination of features - but all are usually accepted as the ne plus ultra competition gun. Perazzi is ONLY about winning, and cosmetics are second to performance.
The 682-series (plus DT & SO) and any Perazzi are lifetime guns - re-buildable infinitely - then can be shopped again and your grandson/daughter can shoot a lifetime, too.
Bob.. respectfully.. none last forever.. But a properly maintained one could go 1,000,000 rounds.. with 2 maybe 3 total rebuilds.. Not just locking bolts.. The hinge pins will eventually wear out and need to be replaced.. and where they contact the barrel will eventually wear out.. and need to be rewelded and recut.. or oversize pins put in.. Both.. over that time will bend the water table and create headspace.. Some of that can be refitted out.. Oversize locking bolts can tighten the area where it slides..
2 years ago.. I saw a new MX2000 destroyed in less than a year by lack of cleaning.. Only handmade locking bolts could ever be used in the future as the channel was .015 oversized..
Saying all this.. even 600,000 rounds is for most.. many lifetimes of shooting.. As the PSI on shells goes up.. the life of the gun goes down..