I've never seen anyone measure wall thickness at a Cabela's store, and I've bought and traded a bunch of guns with them. I know they have people at Sidney who can do it. Elsewhere . . . some of the stores (maybe all?) do have bore and choke gauges now, which didn't used to be the case. A couple of the stores where I've dealt the most keep an "experts list", and will call another Gun Library to get an opinion from a more knowledgeable sxs guy.
Big box stores . . . you just never know. I once offered an SKB sxs to a Scheel's store, on trade. Guy took it back to a manager, came back, said "Sorry, we can't take that gun. It's not on our approved list." Pointed out to him that they had a couple Ithaca SKB's on their rack. "But yours doesn't say Ithaca," he said. He was correct. Mine was a Mitsui-marked gun. Same gun, same SKB manufacture, different importer. And for that matter, the Ithaca still in business at that time was no longer the same Ithaca that had imported the gun. But I figured it was pointless arguing with him since the importer name didn't match, which was the only important thing.
Same thing happened to me at the Scheels here in Bismarck. I wanted to trade a 12ga Brittany (Zabala made SxS with all the bells and whistles) that was imported by BSA, toward a rifle for my son. The clerk told me that he could not take the gun in trade. I asked why, and he said that it was from an unknown maker. I said, BSA or Zabala...his answer, both. He also said that there is no market for "old fashioned" SxS's anymore (this store BTW sells Stoeger Uplanders and CZ Ringnecks). What can you say to that? I also had problems with trying to trade in a Fabarm Classic Lion, but that's another story. So, if you if think Cabela's has problems, try Scheels once!
Best!
Greg