Family Heirloom - Parker DH?

[Nathan Hocking]

Hello all,

I am trying to help my dad identify two shotguns that he recently inherited from his father. I would be very grateful for some help from the experts (relative to me, anyway) identifying this shotgun and understanding if/how it is unique, as well as what it may be worth.

The S/N stamped on all 3 pieces of the gun is 212399. I believe this is a hammerless Parker DH Grade 3, with a Titanic Steel barrel, manufactured in 1925. I don't know what the T with the circle, the HT A in the triangle pattern, the 4 superscript 4, the J.G. in the circle, or the 12, 2, or 3 markings mean. Picture of all the important parts are below.

Please note that (speaking on behalf of my dad), we are not interested in selling the shotguns, and I am definitely not trying to use this website as a platform to peddle a family heirloom!

Thanks so much in advance for any expertise you are willing to share about this shotgun.

Kind Regards,
Nathan