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From eBay:
Description
Period: 1774.
Style: George III.
Dimensions: 117mm x 110mm.
Weight: 92g / 2.96 troy oz.
Condition: Wear commensurate with age and use.
Marks: Bears the makers mark CF as well as full Birmingham hallmarks.
Notes: A stunning item, most likely a mount from an 18th Century sporting gun.
Mike