Lots of shops offer consignment sale services.
I had a sucessful sale at Nagel's and at Trainer Hale Supply.
IIRC I paid 15-20% commission.
That beats the heck out of selling to the shop for 50-60% of retail value.
I've also had some success posting a notice at the gun club.
I hope this helps.
I've sold a few through Dury's. They can buy them outright, put them on consignment, or they can list them for auction at, I think, gunsamerica. The guns that were worth more, a Para P14.45 and AR, I sold through the auction. The lesser-desirable guns I sold outright just to get out of my safe and replenish my gun buyin' pool. IIRC they take less of a cut from the auction, a little more for consignment, and the most from outright purchase.