Approximately .32 caliber. Marked at the barrel ribs Allen & Thurber Worcester " "Allen & Thurber Worchester". Hammer marked "Allen's Patent Mechanically sound. Light wear to the metal components. Actions working as it should, length of 19 cm height 10 cm depth 4 cm, .32 calibre, offering free UK delivery reference DBSS. Tel: +44 7505 165 843 We accept online payments for all our items listed: Bank transfer cash on collection or if wishing over the phone using your debit or credit cards, also doing layby payments plan, or email giving your address details & contact number and we shall send you your items invoice to make payment with your card. Send your request to - john.strong2@gmail.com