Also I'm finding that American shotguns lose value when they have been restored.
Really? You've studied some bonafied restorations; noted the cost of the project gun, the cost of time and materials to restore/refurbish/upgrade/customize it, and found the gun was then worth LESS than it was before?
That's not been my experience. I've refurbished/upgraded more than a few American shotguns and I'm absolutely certain I can sell every one tomorrow for more than I have invested in it. Notice I didn't say "restored." While I can appreciate someone's effort in restoring a tan, 4 door sedan with vinyl seats, I have no interest in owning one, much less investing my time and money to pull it off. The value I place on my guns is satisfaction of a project completed and pride of ownership.
Perhaps you've heard a few people bloviate on the subject and you're confusing their "value" with market value. And when it comes to market value, I'm heartily amused at the agony some people suffer over the loss of a few hundred dollars on a $10,000 shotgun "investment." I wonder what percentage of these people have spent $30,000 on a truck and then had it
appreciate? 
