I've been to a couple of auctions with arms in them at Skinner's... I am reasonably certain they have no one on their staff who knows anything at all about the subject. They are great on clocks, furniture etc. but I suspect they take what the owner says as gospel when it comes to antique arms.
Many years ago I was offered a Henry Pratt NE rifle. It was cut down and converted but I still liked it. I think I offered the lady $500 for it, which was a strong price then and probably still is for a NE rifle in that condition. She told me that "the lady at Skinner's told me it was a Kentucky Rifle and worth at least $2500!" There's no arguing with that. I told her she had better bring it right back to Skinner's and have them sell it. At one of their auctions I bid on a a bit rough but intact steel mounted French fowler made at Tulle... it had very tastefully chiseled mounts and some carving around the tang... probably ca. 1760, very graceful and so much nicer, to my eye, than the over decorated late 18th century guns. It was described as a "French trade gun."
I think they are a good company to do business with but you are completely on your own in making any decision... my own feeling is that if you have to rely on the auctioneer's description, you probably shouldn't be buying at auction.
