The J.M. Davis Gun Museum in Claremore, Oklahoma has a large collection.
In fact, Davis collected so many guns that the building can only hold about 1/3 of them at any given time. It's a large building, too.
(My comments are based on my visit several years ago. They may have changed since then.)
However, probably 90% of the guns are ordinary pieces with no particular historical or artistic or mechanical significance. The collection isn't labeled particularly well; usually there's just a numbered tag hanging off each gun's trigger guard. They all hang in rows and rows of "bookcases" with glass fronts. The museum staff supposedly rotates the stock from time to time so that most or all of the guns get displayed, although I'm not sure why they would really need to bother; if they'd just cull the collection by discarding duplicates and near-duplicates, they could free up most of the space.
Still, in a collection so large, there are bound to be many guns that would match just about anyone's interest. For that reason alone, it's a must-see at some point in every gun nut's life.
A few displays are set up so that the guns have some context, but only a very few. Mostly it seems like a giant gun warehouse. The museum has even shown up on TV news shows in which the talking heads are discussing gun control, with the implication that it is a police evidence locker for the storage of criminally-used firearms.
Next time you're near eastern Oklahoma, drop in for a visit. You won't believe your eyes.
[url]http://www.oklaosf.state.ok.us/~jmdavis/[/url]
[url]http://www.oklaosf.state.ok.us/~jmdavis/inside.html[/url]
[url]http://www.oklaosf.state.ok.us/~jmdavis/davis.html[/url]
P.S. Apparently there's also a Will Rogers Museum in the same town! It might be new, since I didn't hear about it when I drove through a few years ago.