An unusual 7mm walking cane 'blow' gun

An unusual 7mm walking cane 'blow' gun, bamboo clad brass barrel, the brass top unscrewing to reveal a rubber padded mouth piece, the upper section of the stick holding a captive shuttle which, it appears, must be propelled forward by the user's breath until the fixed firing pin protrudes into the rear of the chamber, London Company proof marks, 87 cm (34 in.)