Single shot 12 gauge shotgun

Question
I need to find a source of parts for an old single shot 12 gauge shotgun that still appears to be in pretty good functioning shape.  I would like to refurbish it for use.  Because the markings include scripted "Bay State", but no mention of Worcester, MA, internet postings by others make me think that it was made by Harrington & Richardson sometime after 1909.  No model number is given.

The barrel is 27-13/16" long.  It does not look as if it ever had a front sight.  The hammer is centered and is partially exposed.  The gun finish is well worn, with some deep scratches by an inept attempt at disassembly, but not rusty or pitted.  The wooden butt stock is split and was the victim of a really bad repair using wood screws and glue.  The fore stock is in very good condition.

Total markings are:

   On top of barrel chamber:   12 GA. Choke          A330    

   On left side of action forward of trigger: Pat. Feb. 20 & 27, 1901          Pat. May 14, 1901

   On left side of action above trigger: Bay State  (this is in script)

   Underside of action and behind trigger:        A330
   Buttplate:          Iver Johnson  (means nothing, as probably this butt plate was added to gun much later)

If you can do so, please let me know from whom or from what schematic or listing I might order parts.  Also, it would be helpful to know something about the ammunition that the gun originally was made to handle.

Answer
Bill,

I most often use (with much success) and recommend the Numrich Gun Parts Co. for both out of production parts and schematics/owners manual. They can be reached at www.gunpartscorp.com or by phone to customer service at 866-686-7425. They should be able to help you or recommend another business that can.

Good luck in your quest and thank you for the question.
Sid Lark