MaacK,Good to see JP' gave you a reply with Orig. Info. Are the Barrels engraved on the Top-Rib Sir Joe' Whitworth Steel ?It should show the London Re-Proof stanp on the Barrel-Flats for the Lenghthening of the Chambers by Purdey.(A Script letter "R"). Not advisable to shoot "Hi brass cartridges".Use Care with the 111 Yr old 6.1/2Lb"Classic". dt "Crossed Chisles"