If you look at the Timpo solid figure of a GI with an anti-tank weapon, you may notice that the back end has some kind of cover. People think he is firing a bazooka. Actually, it is a recoilless rifle. The weapon acts like a bazooka in that it has a backblast and is a man-portable antitank weapon. However, it is direct-fire artillery rather than a rocket launcher.
The original M18 recoilless rifle used by the US forces in World War II fires a 57mm diameter projectile. At that time, there was a 57mm antitank gun using conventional ammunition. The antitank gun had greater range and striking power. It also had a recoil and was large enough to need a carriage to move it. The recoilless rifle used a rifled barrel like its wheeled cousin. However, part of the weapon’s energy was exerted out the back of the weapon. To compensate for loss of compression, the little recoilless rifle had to pack three times the propellant of the conventional round. The recoilless rifle had greater accuracy and range than the bazooka and was far less likely to be sent off-course.
While it could be fired from the shoulder like a bazooka, the recoilless rifle was capable of being mounted on the same tripod as a .30 caliber machine gun. That gave it stability, which translates to better accuracy at longer range. The weapon could be put into an open emplacement so long as nothing was behind it.
The big advantage came in the Cold War era with the 106mm recoilless rifle. The HEAT round it fired could disable almost any tank on the battlefield, in its day. Though not man-portable, the weapon could be mounted on a light vehicle such as a jeep. Light, mobile, yet powerful. A crew could fire and speed away before the enemy could return fire.