As a general rule I rate gun dealers (with some exceptions) just about one level above used car salesmen.
That's right, they are dealers... in the business of selling the guns they have in their inventory. Therefore, they aren't very likely to be motivated to provide the tools or information that is going to convince a buyer to look elsewhere.
And even if they had quality bore and barrel wall measuring instruments, there is the little problem of being competent enough to use them properly. Too many people who think they could consistently and accurately measure all along a shotgun bore are the very same folks who couldn't remove a slotted screw in a gun without making it look like the job was done by a caveman with flint tools. So when someone without the skills of a trained journeyman machinist or tool and die-maker gives you some measurements made with sensitive precision measuring tools that are prone to error when used improperly, what makes you think those numbers will be true and accurate? Or maybe ignorance really is bliss. One guy above wants to buy barrel measuring tools, but blew up his Springfield rifle due to a reloading error, and blamed the gun, not himself. Would you trust his measurements if he was selling you a gun?
Chukarman is right. Caveat emptor. Do your own due diligence, and don't be shocked or surprised if a dealer doesn't do it for you. And even if he does provide measurements, you shouldn't believe them until verified.
