The piece required is around 1 1/4 inches long by 3/4 inch wide, thickness is perhaps 1/4 to 3/8 inch leaving lots to cut down to original contour. May have been horn originally but no horn anywhere else on the gun. Proof marks show BP 1887 to 1896. Not a best grade gun by any means but Birmingham built and good quality, back action locks, rebounding hammers, damascus barrels, excellent bores and 2 3/4 inch chambers surprisingly. It will take low brass loads no problem, all kinds of damascus barrels of good manufacture with nitro proofs. You can't go by a lot of the BS you read online regarding damascus barrels. Still proofing them today in the UK.