A VERY RARE ITALIAN OR PORTUGUESE WHEEL-LOCK MECHANISM

Most known examples of this type of lock are not fitted to firearms, but two outstanding complete pistols are preserved respectively in the Instituto Valencia de Don Juan in Madrid (inv. no. 164), and in the Hermitage Museum in St. Petersburg (inv. no. 3.0. 6301). The first is dated 1570-(?), and the second has a carved ivory stock of Singhalese type
See Michael G. Spencer, 'A Note on the "Portuguese" Wheellock', J.A.A.S., vol. XV, no. 4 (September 1996), pp. 220-226