Very nice! Looks to have been sold on by Wilkes at some point.
What a bonus that it came with a Tanner ball mould as well. What weight and barrel length? How are the bores?

The recoil of a 10Bore rifle with Black Powder? Ah, as they say, 'tis but a maidens caress.

- Mike

EDIT: Oh, never mind, I found the Ammoskeag listed details….28" barrels and 12 1/2 lbs…..perfect

See if there is a "Webley number" stamped on or near the fore end hanger as that could give a clue to it's manufacture date.

If it is a brass case rifle your only real source for decent brass is Rocky Mountain Cartridge. I'd not recommend the turned brass sold by Track of the Wolf and headstamped "Parker", as those are very thin and weak at the web.
Of course a Paper Case rifle can easily use modern plastic 10Ga trimmed to 2 7/8"