The Prince of Wales' feathers are there because Dougall had a warrant for the PoW. And NOT because the gun was made for him.
My gun has the same crest on it.
There are no records available. I know about the original owner of my gun because it is written on the rib!
"Made expressly for Charles L. Hunt St Louis"
I am afraid that's all anyone can give you.
Your gun is in a much better shape than mine when I found it. Enjoy it!
Best regards,
WC-