First manufactured in 1856, the side-hammer, cap-and-ball Colt M-1855 revolving rifle was brought into US Army service on a small scale before the Civil War, with only about 100 in inventory. After the Confederates fired on Fort Sumter in April 1861, the “War Between the States” erupted, and the Union Army scrambled to acquire as many rifles as they could to outfit the ever growing number of troops. By the fall of 1863, there were 2,700 Colt M-1855 rifles in Union military service. The pre-war Colt revolving rifles were .44 caliber, 6 shot repeaters, while the wartime procured guns were in .56 caliber and capable of 5 shots. The Colt M-1855 revolving rifle was famously issued to Berdan’s Sharpshooters in January 1862, and then a variety of Union Cavalry units for much of the conflict. Like Colt’s revolving handguns, the .56 caliber revolving rifle was issued with a dual cavity bullet mold to cast both conical and round lead bullets. This US Union Army Civil War Colt M-1855 Revolving Rifle .56 Cal "COLT'S PATENT" Dual Cavity Bullet Mold is in Very Good Condition, with a small “ding” in the middle top front edge, some light fading to the “COLT’S PATENT” marking at the upper front sprue plate, three small nicks just below that marking in the upper front sprue plate, some light stripping to the sprue plate screw head, some light indenting to the upper outer edge of the brass ferrule at the top left wood handle, and with some light overall patina and age wear evident. Most interestingly, it bears the classic “COLT’S / PATENT” mark at the upper front sprue plate, features clean, sharp molds for both conical and round lead .56 caliber bullets, and sports elegant walnut handles with brass ferrules. It remains fully functional, with all parts moving just as they should, and is a fine example of a very rare, original US Union Army Civil War Colt M-1855 Revolving Rifle .56 Cal "COLT'S PATENT" Dual Cavity Bullet Mold.