Regular issue smooth bore muskets were accurate out to 75 yards.  The American Civil War rifle unleashed devastating firepower out to 300 yards.  Prior to and during the War of Secession, artillery was oftentimes used like massive shotguns firing canister out to several hundred yards.  Now for the first time rifled muskets such as the Springfield 1861 and the 1853 Enfields that typically armed the fighting men of the Confederacy could riddle opposing artillerymen as soon as they got within canister range.    Meanwhile frontal assaults that might have once proved successful became suicidal.