Is there any actual documentation to this claim of 6,000 rounds? I don't mean the guy says so and I believe him but something a little more substantial?

I have a friend who has a Biesen built 458 that only got about 4500 rounds through it before it needed to be replaced. That took about 15 years. 300 rounds a year is a lot. How long to shoot a 470 6000 times?