The RT-20 (short for Rucni Top 20) is considered one of the most powerful firearms designed for personal shooting. Rucni Top 20 is translated from Croatian as "hand cannon" and the 20 stands for the caliber in millimeters.
Developed in Croatia in the mid-1990s, the RT-20 was designed as an anti-materiel and anti-armor long-range rifle. It is currently manufactured by the RH-Alan company. The RT-20 had seen some action in the Balkan conflicts since then, and is officially used by the Croatian army.
The RT-20 is single-shot bolt-action rifle in a bullpup configuration. The overall construction of RT-20 is relatively simple, but features a curious solution to work around the recoil of the 20×110mm Hispano rounds that are used in it.
The RT-20 utilizes a reactive counter-recoil tube placed above the barrel. The tube is opened into a reactive nozzle on the rear end above shooter's shoulder, which is also connected to the barrel on the front end in the middle section of barrel. While shooting, a portion of the resulting gasses pass through the recoil tube and out of reactive nozzle, dampening the recoil.
A massive muzzle brake on the barrel further dampens the recoil, making it tolerable for shooting. The RT-20 has no iron sights and is outfitted with telescopic sight that is offset to the left.
The RT-20 has a very long effective range of about 1800 meters and a high terminal effectiveness. Among others, the most prominent disadvantage is the backblast, which is similar to that of the RPG-7.