There is a new version (M4) of the popular M3 Carl Gustav recoilless rifle. There are many improvements. The M4 is 30 percent lighter (at 7 kg/15 pounds) and seven percent shorter (at just under a meter, or 38 inches) than the M3. There is a new electronic sight that is designed to automatically make adjustments to improve accuracy, especially for shots at up to 1,000 meters. This is sometimes done by having the sight transfer data to some of the new rounds that can use that. The new high explosive round has a 1,000 meter range and is lethal out to more than ten meters. The new sight also counts the rounds fired, making it easier to know when maintenance is necessary. The barrel will now last for ten times as many fired rounds (about a thousand). The overall design of the Carl Gustav has been modified and improved based on extensive user experience in combat. This includes things like enabling the operator to carry the M4 into combat with a shell already loaded. Other improvements make it possible for the M4 to accurately fire that round faster and more accurately than in the past. There are new ammo types available as well and more new ones in the works.
U.S. SOCOM (Special Operations Command) has been using the 84mm Carl Gustav for over two decades. Back in 2012 the U.S. Army noted the success of the Carl Gustav with SOCOM and adopted it for all their infantry. The Carl Gustav was adopted by SOCOM for their Ranger Regiment in 1990. While part of the army, the Ranger Regiment is controlled by SOCOM. Ranger NCOs originally came from non-SOCOM infantry units and had been telling their buddies back there about what a handy weapon Carl Gustav was. As a result regular army troops have been demanding the Carl Gustav since the 1990s. Infantry like this weapon mainly because it is a more accurate than rocket launchers and has a longer range than competing weapons (like the Russian RPG). The M1 version of the Carl Gustav was introduced in 1948 and it’s reputation has spread as more countries adopted it.
The Carl Gustav is the first multiple-shot portable large projective weapon U.S. Army infantry have used since the smooth bore 3.5 inch (88mm) bazooka was phased out in the 1960s. The current Carl Gustav (the M3) used is basically a lightweight 8.5 kg (19 pound) recoilless rifle. It is 1.1 meters (3.6 feet) long. The barrel is rifled and good for about a hundred rounds.
The army also got rid of its recoilless rifles in the 1970s, replacing them with anti-tank guided missiles. What made the Carl Gustav unique was that it had the long range of a recoilless rifle (which use rifled barrels) but had a short barrel and was much more portable. The most popular American designed recoilless rifle was the 52 kg (114.5 pound) 75mm M20. With its long barrel (2.1 meters/6.9 feet) the M20 had a range of 6,400 meters. That was fine for use against tanks but the army brass never appreciated the fact that the recoilless rifle was most frequently used against infantry in bunkers or buildings. The Carl Gustav took all this into account and has been very popular with the infantry because of its portability, long range, accuracy and availability.
The 84mm projectiles weigh about 2 kg (4.4 pounds) each and come in several different types (anti-armor, combined anti-armor/high explosive, illumination, and smoke). The anti-armor round is very useful in urban areas and against bunkers. Range is 500-700 meters (depending on type of round fired), but an experienced gunner can hit a large target at up to 1,000 meters.
The army had earlier adopted the single shot version of the Carl Gustav (as the AT4) but the Special Forces showed that the Carl Gustav was better because you get more shots for less weight (the AT4 weighs about 6.8 kg each). It's easier to carry one Carl Gustav, at 8.5 kg, and a bunch of rocket propelled shells at about 2.2 kg (5 pounds, with packaging) each.
What new users of the Carl Gustav have to be most careful with is the back blast, which is more intense than that of the AT4. Army rangers also found that the best way to use the Carl Gustav is with a two man team. One carries and operates the Carl Gustav (and is best armed only with a 9mm pistol as a personal weapon). The other man carried 5-6 rounds of 84mm ammo and operates as a spotter for the Carl Gustav gunner. Depending on the situation, a squad might carry a Carl Gustav instead of a M240 light machine-gun. If you expect to encounter enemy troops some distance away, like over 500 meters, the Carl Gustav is the way to go. The Carl Gustav has been very useful in Afghanistan and any place with wide open spaces. One thing users had to constantly keep in mind was that the 84mm shell did not arm until it was at least 100 meters out. The Carl Gustav shells cost $500-3,000 each, depending on type (and complexity). The launcher (with rifled barrel and sight) costs about $20,000 each.