Rifled breech loader A rifled breech loader ( RBL ) is an artillery piece which , unlike the smooth - bore cannon and rifled muzzle loader ( RML ) which preceded it , has rifling in the barrel and is loaded from the breech at the rear of the gun . The spin imparted by the gun ' s rifling gives projectiles directional stability and increased range . Loading from the rear of the gun leaves the crew less exposed to enemy fire , allows smaller gun emplacements or turrets , and allows a faster rate of fire . Overview . The major problem to be solved with breechloading artillery was obturation : the sealing of the breech after firing to ensure that none of the gases generated by the burning of the propellant ( initially gunpowder ) escaped rearwards through the breech . This was both a safety issue and one of gun performance : all the propellant gas was needed to accelerate the projectile along the barrel . The second problem was speed of operation : how to close the breech before firing and open it after firing as quickly as possible consistent with safety . Two solutions were developed more or less in parallel : The " screw breech " block and " sliding wedge " or " sliding block " . At the time of development of the first modern breechloaders in the mid - 19th century , gunpowder propellant charges for artillery were typically loaded in cloth bags , which combusted totally on firing . Hence , unlike with a metal rifle cartridge , the breech mechanism itself somehow needed to provide obturation . The early " screw " mechanisms for sealing the breech consisted of threaded blocks which were screwed tightly into the breech after loading , but the threads themselves were insufficient to provide a gas - tight seal . This was further complicated by the need to screw and unscrew the breech as quickly as possible : this was met by the " interrupted thread " breech block , where the block circumference was alternately threaded and left unthreaded at a slightly smaller diameter to allow the whole block to be fully inserted and rotated a fraction to lock it . Hence if the block circumference was divided into two sets of threads and gaps , the block only needed to be rotated ¼ turn to lock it instead of several turns . The tradeoff was that only ½ the block ' s circumference was threaded , reducing the security accordingly . The other possibility of sealing the breech was to enclose the propellant charge in a metal cartridge case which expanded on firing and hence sealed the breech , leaving the breech - block merely needing to lock the cartridge case in place . This was more easily accomplished by sliding the block in behind the cartridge case through a vertical or horizontal slot cut through the rear of the breech : the " sliding wedge " or " sliding block " breech . Early breechloaders . The very first cannons of the Middle Ages were breech loaded , with gunpowder and shot contained in pots dropped at the back of the barrel , but the poor seals made them dangerous , and they wore quickly and could not be scaled to larger weapons . Muzzle - loaders were then used until the 19th century . In 1837 Martin von Wahrendorff patented a breech - loader with a cylindrical breech plug secured by a horizontal wedge ; it was adopted by Sweden in 1854 . In 1861 Street & Hungerford Company produced Hughes cannon . It was a breech - loader with the breech of the cannon uniquely like a bolt - action but has no firing pin in its bolt . Armstrong screw breech . Armstrong introduced improved designs in the 1850s and 1860s ( " Armstrong gun s " with his " Armstrong screw " breech ) which involved loading the shell and gunpowder propellant charge ( in a cloth bag ) through the hollow breech screw , lowering a heavy block into a slot behind the powder chamber and screwing the breech screw tightly against the block to lock it in place . A degree of obturation was achieved via a cup on the face of the block being forced into a recessed ring on the chamber face . The system was in effect a vertical sliding block such as later used by Krupp in both horizontal and vertical form , with the crucial difference that Armstrong failed to make the progression to loading the powder charge in a metal cartridge , with the result that complete obturation was impossible : whatever obturation that was achieved relied on manual labour rather than the power of the gun ' s firing , and was hence both uncertain , based on an unsound principle and unsuited to large guns . Armstrong screw - breech guns were initially adopted by the British Army and Royal Navy , but concerns about limited armour penetration of the shells due to limited maximum velocity , safety concerns with the breech blocks blowing out of guns , and higher skill levels demanded of gunners led the British Government to revert to rifled muzzle - loaders from 1865 to 1880 , when Britain finally deployed reliable screw breech mechanisms . The Imperial Japanese Army used Armstrong cannon during the Boshin War to devastate the Aizu castle town and force its inhabitants to surrender quickly , and British Armstrong light field guns proved deadly against Chinese forces in the Second Opium War . However , the British Army and Navy preferred to revert to muzzle - loaders until larger high - powered breech - loaders with secure obturation systems that were relatively simple to operate were developed . Interrupted screw breech . In the meantime the French persevered with trying to develop breechloaders which combined faster loading than muzzle - loaders , high power , safety and solved the problem of obturation : i . e . how to prevent escape of some propellant gas through the breech to the rear . The Lahitolle 95 mm cannon of 1875 with an interrupted screw breech met the first three requirements to a great extent and partially solved the obturation problem . de Bange system . Finally the de Bange system introduced in 1877 solved the obturation problem with an asbestos pad impregnated with grease which expanded and sealed the breech on firing . The de Bange system formed the obturation system for all subsequent screw breeches to the present day . Britain adopted the de Bange breech when it returned to breechloaders in the early 1880s after some initial experiments with the inferior " Armstrong cup " obturation system . Krupp sliding block . Krupp in Germany during this period ( 1864 - 1880s ) in contrast adopted " Horizontal sliding block " breeches , rather than screw breeches , for all artillery calibres up to 16 inch naval guns . This was similar in some ways to the original " Armstrong screw " : the shot and powder cartridge were inserted through the open rear end of the breech into the gun bore , and a steel block was slid home into a horizontal slot cut through the breech to close the rear end of the breech . However , unlike Armstrong , Krupp loaded the powder propellant in a metal cartridge case much like a large rifle cartridge , which expanded against the chamber wall on firing and effectively sealed the breech . The sliding block , in both horizontal and vertical forms , and metal cartridge case continued to be the preferred German breech system until after World War II , and is still used by some modern artillery . Hotchkiss and Nordenfelt sliding - wedge quickfiring guns . From the mid - 1880s Hotchkiss and Nordenfelt introduced 47 - mm and 57 - mm guns which loaded ammunition as a single cartridge with projectile , cartridge case and primer in a single unit as with modern rifle cartridges . The cartridge case sealed the breech on firing and a vertical sliding wedge ( block ) locked it in place . These new guns incorporated recoil control devices which facilitated consistency of aim , allowed single - motion loading and fired as soon as the cartridge was inserted and ejected it after firing : hence the name quick - firing . This set a new standard for artillery , and made firing cycles measured in seconds rather than minutes possible . Elswick coned interrupted screw . Britain enthusiastically adopted the new quickfiring technology , using brass cartridge cases for all calibres up to 6 inches in the late 1880s and early 1890s . However , unlike Krupp and Hotchkiss , British - designed quickfiring ( " QF " in British terminology , which became synonymous with charges in metal cartridge cases ) continued to use screw breech blocks , but with their function merely to lock the cartridge in place rather than provide obturation . The powerful backward force generated by 6 - inch QF guns still required a strongly - seated breech screw with as much thread as possible . However , a basic interrupted - thread screw sufficiently long enough to have enough thread to secure the cartridge on firing still required three separate motions to operate : rotate , withdraw , swing aside after firing , and repeated in reverse before firing . Elswick Ordnance Company ( Armstrong ' s ordnance arm ) developed a coned version of the interrupted - thread screw , with a decreasing rather than constant diameter towards the front . This eliminated the second " withdrawal " motion , with just two motions now necessary : rotate and swing aside . This proved short - lived , with Britain adopting charges in bags using the Welin stepped interrupted screw for all guns 5 inches and up within several years of it becoming available . Bofors ogival screw . Also in the early 1890s , Arent Silfversparre of Bofors invented an ogival screw breech , similar to the Armstrong model in the way it eliminated the need to withdraw the screw before swinging it to the side . Bofors continued to use this in medium artillery into the 20th century . Welin stepped interrupted screw breech . Britain , France and the United States preferred screw breeches for most calibres , but the major drawback of the de Bange interrupted screw as first implemented was that only half of the circumference of the breech block could be threaded , and hence it needed to be fairly long to achieve safe locking of the breech , which required three separate motions to open after firing : rotate to unscrew , retract the screw and swing to the side . Loading required the 3 operations in reverse . This was hence termed a " three motion block " and was slow to operate . Axel Welin solved this problem in 1889 - 1890 with his stepped interrupted screw Welin breech block . This had threads in sets of steps of increasing diameter so that instead of only half of the screw being threaded , the fraction threaded was number of steps / ( 1 + number of steps ) : i . e . if the block of a large gun had four steps of threads , 80 % of the screw was threaded , allowing a much shorter screw and hence breech block . This allowed the block to be unscrewed and swung out in two motions : the " two motion interrupted screw " breech . Further improvements such as that of Smith - Asbury in 1916 allowed the whole action of unscrewing and swinging aside of the breech screw to be accomplished in a single continuous motion , resulting in the " single - motion interrupted screw breech " still in use today . Summary . These rapidly - improving breech systems and the powerful new guns they facilitated led to an arms race in fortification and ironclad warship design that lead to the battleship class of HMS Dreadnought ( 1906 ) and continued until the start of World War I .