An outstanding design by JMB, well made and durable as heck.
A decade ago and more, I received a 12 gauge 11, a family gun with Polychoke. New rings and springs ran less than $20 and a gunsmith friend did a complete teardown, clean and lube. He called it the pkg a 10K round rebuild. He also showed me how to set the rings.
Unfortunately, I was less than happy with the way I shot it. A relative has it now.