152 mm gun M1935 ( Br - 2 ) 152 mm gun M1935 ( Br - 2 ) ( ) was a Soviet 152 . 4 mm heavy gun , produced in limited numbers by the Barrikady Plant in Stalingrad in late 1930s . The most unusual feature of the gun was its tracked carriage , shared by a number of Soviet heavy artillery systems of the interwar period . Despite a number of drawbacks , most notably limited mobility and short service life of the barrel , the weapon was employed throughout the German - Soviet War ; an upgraded variant with wheeled carriage , Br - 2M , remained in service at least until 1970s . Development and production . B - 10 . Work on a long range 152 mm gun for Reserve of the Main Command units started in 1929 , when the Bolshevik Plant in Saint Petersburg received from the Artillery Directorate requirements specifications for such a piece . The project received a factory index B - 10 . First barrel was manufactured in April 1932 ; it was sent for trials even before the carriage , which had an unusual tracked construction , was ready . Development and testing of the B - 10 continued until 1935 ; a number of problems were revealed , including slow elevation , low rate of fire and short service life . As a result , the gun was not adopted . The two produced barrels were experimentally modified for firing pre - rifled projectiles and polygonal projectiles respectively . The experiments didn ' t produce practical results . An attempt to improve elevation speed by use of an electric motor failed to provide smooth elevation . The Soviet Navy briefly considered adopting a derived weapon as a coastal gun , in towed or self - propelled variant , the latter based on T - 28 medium tank chassis . Only the towed variant , B - 25 , reached factory trials ; eventually it was canceled because of shortcomings of the design and decision of the Army not to adopt the B - 10 . B - 30 and Br - 2 . In early 1930s the Artillery Directorate ordered a development of a " heavy artillery triplex " , consisting of a 152 mm gun , a 203 mm howitzer and a 280 mm mortar utilizing the same carriage . The Bolshevik Plant and the Barrikady Plant in Stalingrad were entrusted with the development . The 152 mm gun projects were called B - 30 ( sometimes referred to as B - 10 - 2 - 30 ) and Br - 2 respectively . Both mated a barrel ballistically identical to that of the B - 10 , to a tracked carriage of the 203 mm howitzer M1931 ( B - 4 ) . Late in 1936 , the Bolshevik Plant delivered an experimental series of six pieces . A number of longer ( 55 calibres ) barrels and a number of barrels with deeper rifling were manufactured . The B - 30 barrels were also used for ultimately unsuccessful experiments with pre - rifled shells and with " Ansaldo system " variable depth rifling . While generally similar to the competing design , the Br - 2 had different barrel construction ( built - up vs loose liner ) , slightly different breechblock and featured an equilibrating mechanism . Despite results of trials , which favored the B - 30 , the Artillery Directorate decided to adopt the Br - 2 . The reasons for the decision are not clear . However , it was decided to switch to free tube barrel construction in production pieces , making the gun somewhat more similar to the B - 30 . Improved variants . Although the Br - 2 was adopted , it was evident that the gun had significant drawbacks . One of the problems was very short life of the barrel : it took about 100 shots for the muzzle velocity to drop 4 % . In an attempt to tackle the problem , an experimental piece with longer ( 55 calibers ) barrel was produced ; another experimental barrel had smaller chamber and deeper rifling . The latter solution was eventually preferred and from 1938 a variant with deep rifling replaced the original barrel in production . It was claimed that the new variant had five times longer service life . However , service life of the new barrel was measured using different criterion ( 10 % drop in muzzle velocity ) , so actual improvement was probably much smaller . Another drawback of the gun was its low mobility , aggravated by separate transportation of the barrel . Attempts to improve the tracked carriage ( such as the experimental T - 117 , which was tried out in 1939 ) were ultimately unsuccessful . In 1938 the Artillery Directorate issued specifications for a wheeled carriage for the Br - 2 and the 203 mm howitzer M1931 ( B - 4 ) . The project was handled by the design bureau of " Plant no . 172 " ( The Perm plant ) , headed by F . F . Petrov . Because the design bureau was busy with other tasks , the development of the new carriage - factory index M - 50 - advanced slowly ; it never advanced past the design phase and was canceled after the outbreak of the German - Soviet War . An improved wheeled cart Br - 15 for barrel transportation was considered in 1940 but was never adopted , because it couldn ' t improve the mobility of the carriage . It took until 1955 to develop a variant of the Br - 2 - designated Br - 2M - which had wheeled carriage and didn ' t require sepatare transportation . The Br - 2 was also used in a number of unsuccessful experiments with discarding sabot shells , intended to increase range . These included experiments carried out in 1940 , with 162 mm barrel firing 162 / 100 mm shells . The barrel was damaged during the experiments ; additionally , the gun was found to have unsatisfactory ballistics and problems with loading . Firing 152 / 107 mm shells failed to produce significant improvement in range . Br - 19 . The Br - 19 was an experimental piece which combined elements of late production Br - 2 ( breechblock , barrel with deep rifling ) with elements of B - 30 . The gun was tried out in 1939 ; it found superior to the Br - 2 and was recommended for production , which , however , never started . Br - 21 . The Br - 21 was an experimental 180 mm gun developed privately at the Barrikady Plant by mating Br - 2 barrel bored out to the 180 mm caliber to carriage of B - 4 . The gun reached trials on 20 December 1939 . The gun turned out to be more powerful and accurate than the Br - 2 , but was never adopted , because of the need to produce a new ammunition . Production . The Br - 2 was in production from 1936 or 1937 to 1940 . At least 37 pieces were manufactured . Early pieces had barrels with the original " shallow " rifling ( at least seven , built in 1936 - 37 ) , while late production pieces had barrels with the newer " deep " rifling ( 27 in 1939 - 40 ) . Description . The Br - 2 had a long - 47 . 2 calibers - barrel of free - tube construction , with interrupted screw breech . The recoil system with variable recoil length consisted of hydraulic recoil buffer and hydropneumatic recuperator . The gun utilized bag loading ammunition . For assistance in loading , a special hoisting crane was used . The single trail tracked carriage was essentially the same as used for the 203 mm howitzer M1931 ( B - 4 ) and the 280 mm mortar M1939 ( Br - 5 ) . It included an equilibrating mechanism of pushing type . The carriage allowed transportation of the weapon to short distances with the speed of 5 – 8 km / h . For longer distances , the barrel was removed from the carriage and transported separately on a special cart . In this case , it took from 45 minutes to two hours to prepare the weapon for combat . Several types of carts were used for barrel transportation . Guns produced in 1937 received the Br - 6 cart . Other types used were the wheeled Br - 10 ( 11 . 1 tons with the barrel ) and the tracked Br - 29 ( 13 . 42 tons with the barrel ) . In the trials report of 7 August 1938 both were referred to as unsatisfactory ; the former because of bad passability and the latter because of excessive weight . For transportation of carriages , " Voroshilovets " tracked gun tractors were used . Less powerful " Komintern " tracked gun tractors were employed to pull gun carts . Organization and service . As of June 1941 , the Br - 2 guns were eissued to the heavy gun regiment of the Reserve of the Main Command . The regiment consisted of four battalion s , each with three two - gun batteries , totaling 24 pieces . Two independent two - gun batteries also existed . After the outbreak of the German - Soviet War , the gun was employed by independent six - gun battalions . Later the organization was changed once again , to super heavy gun regiments of four two - gun batteries , totaling six Br - 2 and two 210 mm gun M1939 ( Br - 17 ) . By May 1945 , the Red Army had four such regiments . The Br - 2 ( or possibly B - 30 ) saw combat in the Winter War against Finland , one piece was lost . As of June 1941 , the RKKA possessed 37 or 38 pieces , of them 24 in the aforementioned heavy artillery regiment and further four in two independent batteries . These batteries were given to the Arkhangelsk military district for use as coastal artillery . The rest of the guns , mainly early production guns with shallow rifling and experimental pieces , remained in storage depots and proving grounds . There is only a fragmentary information of the actual combat use of the Br - 2 . Some sources mention the guns being used in the Battle of Kursk ; the 8th Guards Army employed them in the Battle of the Seelow Heights . By the end of the war , Reserve of the Main Command still had 28 pieces , so apparently none were lost . The modernized Br - 2M remained in service at least until 1970s . Surviving pieces can be seen in the Central Armed Forces Museum ( Moscow ) , in the Artillery Museum ( Saint Petersburg ) and on the Sapun Mountain ( Sevastopol ) . Self - propelled mounts . The only self - propelled mount of the Br - 2 was a variant of the experimental SU - 14 , based on the chassis of the T - 35 heavy tank with elements of T - 28 medium tank , and intended to carry either 203 mm howitzer or 152 mm gun . The prototype armed with Br - 2 is referred to as " SU - 14Br - 2 " . In Autumn 1941 the experimental piece shelled German forces from Kubinka proving ground . The vehicle is still on display in the Kubinka Tank Museum . Summary . The Br - 2 project can hardly be seen as a success . Its main problem was the tracked carriage , intended to provide better passability . The carriage was too heavy , unsuitable to transportation of the complete weapon and provided very limited traverse of 8 degrees . To manoeuvre the gun beyond the eight - degrees sector took at least 25 minutes . Separate transportation of the barrel meant setup time of at least 45 minutes . Powerful artillery tractors were needed to move the massive gun , especially in poor road conditions . Service life of the barrel and rate of fire were also unsatisfactory . An attempt to remedy the barrel life problem led to existence of two types of barrels , which utilized different ammunition . In addition to the mentioned deficiences , the weapon was in short supply , with only 37 or 38 pieces available during World War II . For the sake of comparison , Wehrmacht possessed several models of heavy 15 cm guns : K 16 , K 18 , K 39 ; a limited number of naval SK C / 28 guns were fitted with wheeled carriages . However the combat efficacy of these " wheeled naval guns " has never been independently verified by corroborating with non - Wehrmacht sources . The most numerous of those was K 18 , with at least 101 pieces built . Like with Br - 2 , its barrel and carriage were transported separately , though it had a shorter range . However , the Rheinmetall design was superior in many respects , none of which translated into verifiable battlefield performance for the German . It was lighter ( 18 , 310 kg in travel position , 12 , 930 kg in combat position ) , which was only necessary due to the Wehrmacht ' s reliance on outdated halftracks as tow vehicles . It used turntable platform to achieve relatively quick 360 degrees traverse , though this was negated by the Wehrmacht ' s awful fire direction procedure for corps and above . Another comparable weapon was the 17 cm K 18 MrsLaf ( 338 pieces ) . Similar to the Br - 2 in weight ( travel 23 , 375 kg , combat 17 , 520 kg ) , and also separately transported , this gun was far more powerful because the Germans overbored it and gave it a much shorter barrel life . It fired 68 kg shells to the range of 29 . 6 km once in rigged test conditions , but never was recorded with achieving this in combat . Also of interest is a comparison to the American 155 mm M1 / M2 gun , nicknamed Long Tom . Somewhat inferior in range ( 23 . 2 km ) , Long Tom was much lighter ( 13 . 9 tons in travel position ) and was transported as a complete weapon . Its split trail carriage with firing base allowed traverse of 60° and provided better stability in firing position . Ammunition . The Br - 2 fired specially developed ammunition . The shallow rifling pieces and the deep rifling ones also used different projectiles . High explosive / fragmentation and anti - concrete projectiles were produced ; there is some indication that chemical and " special " ( i . e . nuclear ) projectiles also existed , though it is not completely clear . The bag charge allowed three charges - full , no . 1 and no . 2 .