Development began in 1942 of a dual-purpose field and anti-tank gun that could be built in Romania to replace the collection of obsolescent field guns currently used and upgrade their anti-tank defenses of the army. To speed development Colonel Valerian Nestorescu suggested combining the best features from the guns already in service in Romania, Germany or captured from the Soviets. Colonel Nestorescu was selected to produce a prototype to be built at the Uzinele şi Domeniile Reşiţa in Reşiţa. Three prototypes were built combining various features and trialled against the ZiS-3, a Reşiţa-built copy of the ZiS-3, the Pak 40 and the Schneider–Putilov Model 1902/36 field gun in September 1943 and the third prototype had the greatest armor penetration. It was adopted as the Tunul antitanc DT-UDR 26, cal. 75 mm, md. 1943, commonly shortened to 75 mm Reşiţa Model 1943.
Description
The gun combined the muzzle brake, recoil and firing mechanisms and split-trail carriage of the ZiS-3, the barrel, rifling and cartridge chamber of the Vickers/Reşiţa Model 1936 anti-aircraft gun and the projectile chamber of the Pak 40. It had a gun shield that consisted of two plates separated by a gap. It had only 680 parts, almost as few as the 610 of the ZiS-3, but far fewer than the 1200 of the Pak 40. It had a higher muzzle velocity and thus greater penetrative power than the Pak 40. It therefore combined virtues of both the ZiS-3 and Pak 40. 1100 guns were ordered on 10 December 1943 from Uzinele și Domeniile Reșița, Astra in Braşov and Concordia in Ploieşti. The 75 mm Reșița Model 1943 fired a armor-piercing shell at. Penetration test consisted of eight armored shields with a thickness of 10 cm placed as follows: the first four were 300 meters, the other three at 500 meters and the last one at 1000 meters and they lasted a total of one minute and twenty seconds. The performance of the cannon was as follows: complete destruction of the first four shields at 300 meters, complete penetration of the three at 500 meters and penetrating the one at 1000 meters. However, this high muzzle velocity came at the cost of a very short barrel life, only 500 rounds, compared to the 6000 of a Pak 40. Its ammunition combined features of shells used by the Pak 40 and the Vickers/Reșița Model 1936 anti-aircraft gun, although this raises the issue of exactly how the Reșița Model 1943 achieved such velocities. The Pak 40 had a muzzle velocity of when firing the light-weight, tungsten-cored Pzgr 40 shell, but the only data for the Reșița give a shell weight of, which is roughly equivalent to the Pak 40's full-sized Pzgr 39 shell that was fired at a mere. Unfortunately detailed specifications for the Reșița's ammunition haven't been discovered so that question will have to remain unanswered. The 75 mm Reșița Model 1943 had a maximum elevation angle of 35 degrees, which allowed it to also be employed as a field gun. This was almost as much as the 37 degrees of the Soviet ZiS-3, a dedicated field gun, and significantly more than the 22 degrees of the German Pak-40 anti-tank gun. It could also depress slightly more than both. This made the Romanian gun arguably the most versatile in its class during World War II, outperforming its Western, German and Soviet equivalents.
Operational use
The first twenty-four guns were issued to the 1st Armored Division in the spring of 1944 and later two independent anti-tank regiments with thirty-six guns apiece formed from the artillery regiments of the disbanded Frontier Division. Most of the cavalry and infantry divisions began to receive some guns during the summer of 1944. A total of 372 pieces were produced: 210 at the Reșița works, 120 at the Astra Works in Brașov and 42 at the Concordia Works in Ploiești. However, the gun displayed in Oradea has serial number 394, thus the production run was likely larger. Despite the losses suffered during the Soviet Jassy-Kishniev Offensive of August 1944 most divisions at the front in February 1945 had between six and twelve 75 mm Reșița Model 1943 on hand. After the war, the gun was relegated to secondary roles, such as training, because it had a western caliber. The 75 mm Reșița Model 1943 was used until 1998, when it was phased out. The gun was also used on the later prototypes of the Mareșal tank destroyer. An almost complete example, lacking optical sights, is displayed at the Romanian National Military Museum in Bucharest. Five more are displayed in various places around the country – one on the sidewalk in front of the Military Museum in Oradea, two more in Libertatii Square in Timișoara, one in the Dej Military Museum and, finally, one at the Military Museum in Constanța.
