The German LG40 series utilized two specific types of projectiles - a High-Explosive (75x130mm R HE) and an Armor-Piercing (75x200mm R AP) type. These were simply modified variants of existing artillery shells, differentiated only by their cartridge casings (made of paper), which significantly sped up manufacture of each breed. The HE variant was the 7.5cm (75mm) Gebirgsgeschutz 36 while the AP variant was the 7.5cm Feldkanone 16 (New Model) and the 75mm caliber design of the projectile allowed it to be extremely powerful by 1930s/1940s battlefield standards (the same caliber of projectile was used in the Panzer 4 medium tank for example). The 75mm projectile of the LG40 was loaded through the breech of the weapon (as opposed to the muzzle end of the barrel as in a field mortar) utilizing a handle atop the breech which slid the block to the right side, thusly exposing the now-open barrel base for insertion of the 75mm shell.
The weapon, as a whole, weighed several hundred pounds and the barrel (with a tapered neck ahead of its middle section) sported a running length of 1.5 feet (2.5 feet when secured to its mounting support system). The breech consisted of a horizontal sliding breech block similar to those uses by field artillery systems. The gun barrel could be elevated (via a hand wheel) between -15 and +42 degrees for varying attack angles and traverse was effectively a full 360-degrees when attacking line-of-sight targets. A trained and experienced gunnery crew could fire approximately 3 to 6 rounds per minute out to 7,400 yards, giving paratroopers a good "reach" on the battlefield against enemy armor, troop concentrations and even fortifications (the latter to a certain extent). The launch tube sat on a two-wheeled trolley that featured metal (aluminum/magnesium alloy) support legs. The relatively compact size of the entire unit allowed for airdropping via parachute and relocation was simply by two crew grabbing a rear leg of the wheeled carriage and moving the weapon into position.
With the war in Europe now in full swing by 1941, the LG40 was in serial production and fielded in the German invasion of Crete (spawning the famous "Battle of Crete"). The battle commenced on May 20th, 1941 and would last some 11 days as 14,000 German paratroopers were flown in and supported by bombers, gliders and allied units in the attack on positions held by British, Greek, Australian and New Zealand troops. The campaign cost over 23,800 Allies to the comparatively low Axis total of 6,698 (2,700 Italian troops supported the Germans in the assault) and proved an utter German-Axis success early in the war.
The LG40 was fielded in the invasion across two parachute artillery batteries. Troopers enjoyed the relatively lightweight nature of the design and the hitting power of their 75mm shells against all manner of targets. The weapon could fire and be quickly relocated to fire again within minutes and engagement across uneven terrain allowed for firing in elevated mountainous areas. However, the LG40 design was not without its faults for the gas expulsion system proved temperamental and the mounting support system was prone to breakage after extended use. It is notable that neither issue restricted overall use of the weapon during its service life which ran over the entire course of the war -the LG40 saw service into 1945 (the final year of the war). Captured specimens by the Allies proved that the LG40 did in fact offer little to no recoil in practice.
In all, 450 LG40 guns were produced for the German air and land forces (including the Waffen-SS). The success of the 7.5cm LG40 weapon in Crete ushered in the larger-caliber Krupp "10cm LG40" design of 1942.