revolver. The barrel is approximately 3 inches long. The cylinder is engraved with a scene of forest animals identical to the 'belt-size' side-hammer percussion revolver, and a few examples have the frame surface finely engraved as well. As with many models, changes were made during production, and collectors note an 'early' and 'late' variation. Large frame Bar-Hammer revolver The large frame is a five-shot, .34 caliber revolver. The barrel is 3.5-4 inches long. The cylinder is engraved with a scene of forest animals identical to the 'belt-size' side-hammer percussion revolver, and a few examples have the frame surface finely engraved as well. As with many models, changes were made during production, and collectors note an 'early' and 'late' variation. Side-Hammer percussion revolver The author has found the side-hammer models to be the most interesting of all of the Allen revolvers. Allen's design was clearly influenced by Colt's 1855 'Root' revolver, adopting the top strap above the cylinder for strength, rigidity and thus accuracy, and the side-hammer rather than the center hammer more usual on the Colt models 1847, 1848, 1849 and 1851. Another 'borrowed' feature was that the cylinder pin unscrewed from the rear, which the author finds far superior to the various methods of removing to the fore of the pistol. Though influenced by this near contemporary, Allen attempted to build the 'better mousetrap' by incorporating several unique and patented design features. One change was to retain standard trigger used in the bar-hammer revolvers rather than Root's spur trigger. The most interesting new feature is the combination trigger guard / loading lever. Unlike Colts, Remingtons, and other percussion revolvers that aligned a lever to load the cylinders under the barrel, Allen designed his revolvers to incorporate the trigger guard for this function. A catch is tripped, and the trigger guard and attached arm swing down to push a rammer into the bottom cylinder, thus seating the ball fully into the chamber. This reduced the number of parts, and likely cost of manufacture. This patented, unique feature carried on into the later center-hammer percussion models. There were four distinct cylinders, varying in the machining. All models are single action. Finish was blued, with wood grips as standard. Ivory or silver grips could be had for an additional cost. Though manufactured in much smaller numbers than the Colts, Remingtons, Starr and other revolvers of the Civil War, Allen and Wheelock revolvers