Read footnote 14a. Towards the bottom, it says approximately 1500 rounds for the liner. Very interesting about how rounds through the barrel increased exponentially. I’m not sure, but I think it is the liner that needs replacing, not the barrel.
http://www.navweaps.com/Weapons/WNUS_16-50_mk7.php#ammonote14
He was quoting the Mark 6’s barrel life numbers, you’re quoting the correct one for the Iowa’s Mark 7s. Yes, they just swap out the barrel liner when that’s worn.
“it is the liner that needs replacing, not the barrel.”
https://apps.dtic.mil/dtic/tr/fulltext/u2/a183947.pdf
The shrunk fit asembly was accomplished in a deep electrically
heated pit. First the jacket was heated to cause expansion. A tube
was then placed in the pit, breech end down, with a centering
mandril extending up into the bore for support. cold circulating
water cooled the tube and prevented it from expanding. The jacket,
which had expanded in diameter, was then slipped on over the tube.
Cooled, the jacket contracted and gripped the tube firmly and
evenly,
“Very interesting about how rounds through the barrel increased exponentially”
Too much fun stuff to read!
I’m easily amused and it is raining out...
At a site I lost track of, it was noted that advances in erosion control made the mechanical properties of the barrel the more important consideration.