The point of this thread is a good one. Dealers who sell large numbers of guns are not uninformed about what and how to measure things as a rule. If I as a minor collector, can justify the cost of tools to measure guns completely and can learn how to use them correctly, then a dealer certainly can do so as well. And if they do know why would they not be willing to pass along all the information unless it hurts their cause to sell a gun.
We have no proof laws in this country to protect the consumer for guns that are in unsafe condition. A visual inspection is not adequate in this case. I suspect most dealers take one of two pathways. They choose to never know, so they can always resort to it is up to the seller to have the gun inspected before use in case of a problem or they know and do not want to share all the information with the buyer. You might still buy a gun with thinner barrels, but it would become a point of negotiation if you knew they are thin or you might just walk away completely. That $6,000 gun may be more like a $3,000 gun with thin barrels. It certainly will be a lot harder to sell to an informed buyer.
