Need advice, which auction house would/did you use?

[GHPA]

Hello everyone. Looking to sell my Parker GH, which auction house would/did you use? Also, I recently had a local appraisal done. Since the very knowledgeable members here see these on a daily basis, I would appreciate their opinions as well on its condition and value. The history, this was my grandfather's and when he passed it went to my father and then when he passed ten years ago to me. Serial number 201545, Model GH 12ga. with 30" Damascus barrels and 2 1/2" chambers with ejectors. The appraisal says 99%+ casehardening remains along with 99%+ scroll engraving on all sides and game bird scenes on the left and right sides and on the underside. 99%+ checkering on the forearm, pistol grip stock with grip cap, silver initial shield and Parker logo butt plate. Lastly, he states "Shotgun appears in like new condition and possibly unfired". I was only allowed five pictures, if possible I will add more pictures later. Thank you in advance, Robert