Looking to downsize my firearm collection, does anyone know about a
firearm consignment shop in central Florida (Belleview/Ocala area)?

None that I know of that won't try to hose you. Why not try the EE on here with LOCAL FTF FLORIDA deals preferred? Depending on what you have, gun prices are not strong right now IMO, the election results have turned it to a buyers market... then add on a competitive lower price to be able to move the gun minus the selling fee... not sure it would benefit you.

Maybe try a couple first on the EE and go from there?

I agree...try the EE or Fl Gun Trader.  You'll be lucky to get half the value of your firearms selling to any kind of dealer.

The dealers in my area (Brevard) want as much as 20% commission, with the average about 12%.

You're better off selling on the EE, FL Gun Trader or Gun Broker.

Got any three screw rugers?

I agree with what everyone else says and I'm an FFL dealer. If you turn them over for consignment, you'll have to fill out a 4473 and pay a NICS to get them back if they don't sell. I know of one dealer that charged a customer a substantial cleaning fee on each gun to get their guns back. You'll be dollars ahead to sell them yourself. If you want to CYA on the sale, you can bring the customer to the dealer and have the dealer run a NICS and do a 4473. Dealer will log the gun from you and out to the new buyer. I would expect the fee to be nominal, $25 would be a reasonable expectation.