The first Trapdoor Springfield, a conversion of Civil War surplus Model 1863 rifle-muskets using Erskine Allin's hinged breech design. Chambered in .50-70 Government — the first standard US centerfire military cartridge. The conversion allowed the Army to modernize without replacing its vast stock of Civil War muskets. Inexpensive and practical, if not the most advanced design of the era. Type: Rifle Action: Trapdoor Caliber: .50-70 Government Capacity: 1 Year introduced: 1866, USA Weight: 128 oz Overall length: 44" Status: Discontinued Military use: Yes Intended use: military