I was there last summer. I went with a friend who wanted to buy a couple of their guns over the counter.
Yeah, it's a lot bigger on the outside than it is on the inside. The interior space is mostly warehousing, packaging, offices. But the part that is accessible to the public is pretty dense with things to look at.
Before you get inside you see black powder cannon barrels on the sidewalk. That get's you in the mood.
I'm a big fan of the written page and they had a variety of books, magazines and some magazine back issues. (I bought a bunch of Gun Reports.) One wall is Turners collection of muzzleloading long guns. It's an eclectic collection, but bring your glasses to read the tags and you'll see a variety of interesting items.
There is also a small but interesting inventory of unmentionable guns. It was a thin selection that included mostly older or classic handguns.
Turner's museum of Americana is intriguing if you're into it. It's not all glitzy like a big city museum, but it is packed with stuff that interested Turner - and interested me! Lots of early cars - lots. All sorts of antique utility steam engines, some set into an operable display where you can pick different engines and watch them operate via compressed air. All sorts of different antique gizmos and collections of items. The old gunsmith display had a number of hand powered drilling and boring rigs. A portion of log cabin displays many hand tools and intriguing manual machinery on benches.
The museum feels a bit neglected. But it is a fascinating bunch of stuff!