Righto- Old Chap- on page 601 of my 9th (and last) edition of W.W. Greener's "The Gun and Its (sic) Development- said device is well illustrated. I just lowered the price of my MINT copy of this last edition- 1910 with DJ and frontis ils. from $100.00 to $80.00 including USPS bulk rate shipping-prepaid by USPS money order. This final edition has details on single triggers, and several chapters of live bird shooting- a Must read for all you shotgun lads who are detail oriented- RWTF

"The field is the touchstone of the man"..