William Moore and Sons double barrel shotgun
Yes, that's true. That company did make a double barreled shotgun. It was actually made by the Liege company of Belgium. Your gun is a knock-off of an earlier design patented by the William Moore Firearms Co., an English firm. Moore never did business as William or Wm Moore and Sons. It was probably made somewhere between 1875 and 1900, so even though it's a knock-off (near copy) it may have some value as a collectible.
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