Rifle calibre machine guns were needed to repel boarders in an era when close quarter encounters, ramming and boarding were still major tactics. The advantage of a gun which could pour hundreds of rounds a minute, using only a crew of 2 or 3 was of immense value. The first such gun into Royal Navy service was the Gatling, but this proved heavy and unreliable using the ammunition that was supplied. The Nordenfelt 5- and 10-barrel volley machine guns were considerably lighter and could therefore be mounted in the fighting tops and on small boats for landing parties.
5-Barrel Rifle-Calibre Gun
Mk I 5-barrel Nordenfelt with late pattern distributor and hopper (Royal Armouries, Leeds)
Late and Early designs of Hopper [N3]
Late design hopper and distributor
Old design of hopper and distributor
Motion of action block through links to quarter-circle segment cams (rollover)
Mk II 5-barrel Nordenfelt (National Maritime Museum)
The 5-barrel rifle-calibre machine gun was capable of a maximum (quoted) rate of fire of 600 rounds per minute (or 120 volleys a minute). Aimed and sustained fire would be slower. As it fired the same cartridge as rifles, the efective range would be 300 - 400 yards. although as the barrels were mounted on a solid, non-recoil mounting, accuracy would have been better that individual rifles.
The first model 5-barrel guns (Mark I) used a variant of Nordenfelt's First System mechanism (Palmcrantz). These can be recognised by the action plate which moves backwards out of the gun mounting when the operating lever is pulled to the rear. Later, Mark II, guns used the Second System, as illustrated by the 2-barrel 1" Nordenfelt gun on this site.
Ammunition feed was important. The simple mechanism used by Nordenfelt had to be customised for each variant of rifle cartridge used by the various National customers, however, it seems to have been the only one that could reliably fire the Boxer cartridge issued for use in Martini-Henry rifles. This cartridge was formed by rolling sheet brass and paper into a cylinder, then riveting it to a baseplate. Eventually, technical knowledge advanced to permit solid cartridges to be drawn from solid copper, and these proved immensely superior.
The feed mechanism consisted of two detachable hoppers. The lower one, also known as the distributor, had a number of channels fanning out downwards to conduct cartridges to each barrel. Distributors usually contained up to 10 cartridges per barrel.
The upper hopper was placed over the distributor, and a catch released the cartridges to recharge the distributor. The upper hopper would be replaced each time it became empty, thereby allowing the gun to continue firing the reserve of cartridges in the distributor. The upper hopper does not seem to have been attached by a catch to the distributor, so there was a risk of it becoming detached if the gun were pointed steeply downwards (as from a fighting platform in the mast).
Drawings of Nordenfelt rifle-calibre machine guns usually show the distributor with cut-outs front and rear. These are the early pattern of hoppers, typically firing the Boxer cartridge, where the cartridges were loaded with a nose-down aspect. It was possible that the loose arrangement of cartridges in a column could cause them to stick in a hopper, so the cutouts were provided so that the gunners could release a sticking cartridges using a short pin.
The improved hoppers, made for solid drawn brass cartridges, were loaded from the top, and the nose of the bullet touched the front of the hopper while the base plate was constrained by grooves in the columns. These cartridges remained in a nose-up attitude until they reached the base of the distributor, where there was space for them to fall horizontally onto the slots over the cartridge carriers.
Mechanism of the Mark I 5-Barrel Nordenfelt
The animation shows the operation of the modified First System used in Mark I guns, and also assumes the use of the Boxer cartridge.
The mechanism of the 5-barrel rifle-calibre machine gun is nearly the same as that described for the 4-barrel 1 inch anti-torpedo boat gun, with the principal exception that is described below. The action block, which consists of the mounting plate carrying the five hammers and springs, and on the front face the five plungers that ram the cartridges into the barrels and seal the breeches, is moved backwards and forwards by pivot arms that are connected at the front of the action block and to two quarter-circle segment gears wheels at the rear. As the firing arm is moved to the rear, a friction roller moves within a slot in one of the quarter circle segments, causing it to rotate. The arms then pull the action block to the rear.
When the firing lever is pushed forwards, the action block is driven forwards, pushing the fresh cartridges into the barrels. As the plungers reach their furthest extent, the heels of the connecting arms are carried into recesses on either side of the inner part of the framework, thus locking the action block in place and absorbing the recoil of the gun.
Mechanism of Mark II 5-barrel Nordenfelt
Later versions of the Nordenfelt 5-barrel rifle-calibre machine guns used Nordenfelt's Second System, as shown in the page on the 2-barrel 1 inch gun, but with 5 barrels, plungers etc.
Nordenfelt 5-barrel rifle-calibre machine gun, Mark I, which used an adaptation of Nordenfelt's First System. Later Mark II models used the Second System, similar to the 2-barrel 1" machine gun described in this web site.