page_title: 3-inch ordnance rifle
section_title: Specifications
hierarchical_section_title: 3-inch ordnance rifle / Specifications
caption_attribution_description: English: Photo shows a 3-inch Ordnance rifle along Hancock Avenue at Gettysburg National Military Park near the Company A, 1st Rhode Island Light Artillery monument. Directly in front is "The Angle" - the target of Pickett's Charge. View is toward the west.
context_page_description: The 3-inch ordnance rifle, model 1861 was a wrought iron muzzle-loading rifled cannon that was adopted by the United States Army in 1861 and widely used in field artillery units during the American Civil War. It fired a 9.5 lb projectile to a distance of 1,830 yd at an elevation of 5°. The 3-inch rifle was not as effective in firing canister shot as the heavier 12-pounder Napoleon, but it proved to be highly accurate at longer ranges when firing shell or shrapnel. There was only one reported case of a 3-inch ordnance rifle bursting in action. This was in stark contrast to the similarly-sized cast iron 10-pounder Parrott rifles which occasionally burst without warning, inflicting injury on the gun crews. The Confederate States of America lacked the technology to manufacture successful copies of the 3-inch ordnance rifle. However, the Confederate States Army respected the weapons and employed those captured from Federal forces.
context_section_description: The ordnance rifle had a bore (caliber) with a diameter of 3.0 in (76 mm). Its gun barrel weighed 820 lb (371.9 kg) and fired a projectile weighing 9.5 lb (4.3 kg). The gunpowder charge weighed 1.0 lb (0.5 kg) and fired the projectile with a muzzle velocity of 1,215 ft/s (370 m/s) to a distance of 1,830 yd (1,673 m) at 5° elevation. The 3-inch rifle could hurl a shell 4,180 yd (3,822 m) at 16° elevation. Unlike a smoothbore cannon, the 3-inch rifle's projectile retained two-thirds of its muzzle velocity at 1,500 yd (1,372 m) – or 839 ft/s (256 m/s) – so that its rifled projectile was invisible in flight. A smoothbore cannon's projectile retained only one-third of its muzzle velocity at that range and its round shot could be seen in the air. However, a rifled projectile could become visible if the shell began to tumble out of control. Tumbling occurred when the shell failed to take the grooves inside the gun barrel or when the spin wore off in flight. The 3-inch gun's rifling consisted of seven lands and grooves with a right-hand twist. The twist rate was one turn in 11 ft (3.4 m).
  The 3-inch ordnance rifle was mounted on the standard carriage for the 6-pounder field gun. Because its projectile was heavier than a 6-pound shot, the 3-inch rifle's greater recoil sometimes caused damage to the trail or the cheek pieces of the carriage. The 6-pounder carriage weighed 900 lb (408 kg). The 3-inch rifle fired case shot (shrapnel), time and percussion shell, and canister shot. The use of bolts (solid shot) was rare. Either Hotchkiss or Schenkl ammunition could be used. Parrott ammunition could be used in an emergency, but it performed poorly since it was designed for the 10-pounder Parrott gun which had only three grooves, rather than the ordnance rifle's seven grooves. For two reasons, canister shot fired from the 3-inch rifle was less effective than canister fired from a 12-pounder Napoleon or a M1841 12-pounder howitzer. First, its 3-inch bore was narrower than the 12-pounder's bore and could blast fewer canister balls. Second, the rifling of the barrel caused the canister to be thrown in an irregular pattern. For these reasons, Union General Henry Jackson Hunt believed that the 3-inch ordnance rifle's effective canister range was less than half that of the 12-pounder Napoleon's 400 yd (366 m) range.
  Early in the war, Union batteries were organized with six guns of identical type. At the Battle of Gettysburg on 1–3 July 1863, 50 of the 65 Union batteries numbered six guns and 64 of those batteries had guns of identical type. The exception was Sterling's 2nd Connecticut Light Artillery Battery. Each 6-gun battery required 14 6-horse teams and seven spare horses. The teams pulled the six artillery pieces and limbers, six caissons, one battery wagon, and one traveling forge. Each caisson carried two ammunition chests. The limber carried one additional ammunition chest. The 3-inch ordnance rifle carried 50 rounds in each ammunition chest. A memo from November 1863 stated that rifled guns ought to have 25 shells, 20 shrapnel (case shot), and five canister rounds in each ammunition chest. In March 1865, a memo recommended that each chest carry 30 shell, 15 shrapnel, and five canister rounds for rifled guns of the horse artillery.
caption: This 3-inch ordnance rifle overlooks "The Angle" – the target of Pickett's Charge – at Gettysburg National Military Park.
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