Looking for some help with an family heirloom.

Trying to import from Canada to US, a .38 S&W model 30C. Grandfather's Grandfather purchased the firearm new to move West. ATF disapproved my import application, not sure exactly why, but the importer I used said the criteria for barrel length vs size was within parameters and he was very surprised this was disapproved.

So I'm trying to figure out where to go from here. Two thoughts I have is there precidence for the import of this same model that I could convince ATF to reverse their position, and is this pistol possibly an antique. The antique approach would require me to prove it's pre 1898 mfg, which I have know idea how to do.

Any help would be greatly appreciated. I have photos if that would help anyone