Armslist.com is a local internet site, you can check to see if they have a local branch. Gunbroker.com is the eBay of guns. for unusual guns it might be a better option as it is nationwide. This forum and the coltforum.com have for sale forums, but you need to have a minimum number of posts. Ebay would be a good place to list gun parts, dies, etc.
A spring gun show isn't a bad idea. If your guns are at all off beat, and it sounds like some are, selling online seems better to me. The trouble with Armslist.com is you may encounter someone who will try and rob you. This has been a problem some places with Craigslist. (Craigslist doesn't sell guns).
Do your research and find a good price range. Also, I would say good pictures are a must. I have a favorite pawn shop I sometimes sell guns to. IMO, at the prices he pays I lose about $100 on a $1000 gun or $50 on cheaper guns over top retail. I would be concerned about selling him 40 guns though.
If you sell on Gunbroker and don't have much feedback that is a big turn off to some folks. Also if you don't offer to take a credit card, folks get concerned that once they pay for the gun they may never hear from you. Also it is a hassle, but some folks offer a 3 day return privilege assuming the gun isn't fired. If you have good feedback on eBay, i have seen gunbroker sellers reference that. Having one or two (or three or four) guns as trading stock is kind of neat, having 40 to dispose of is a Pain.