Many people don't know that the Germans had a barrel for their Sturmewehrs in WW2 to shoot around corners. The Krummlauf (curved barrel) was an attachment for the Sturmgewehr 44 rifle, which was used by the Germans in World War II. It allowed the shooter to aim and fire around corners with its bent barrel and a periscope-style sight. A disadvantage of the device was its short life, due to the stress of firing.

It was produced in several variants: an "I" version for infantry use, a "P" version for use in tanks (to cover the dead areas in the close range around the tank, to defend against assaulting infantry), versions with 30°, 45°, 60° and 90° bends, a version for the StG 44 and one for the MG 42. Only the 30° "I" version for the StG 44 was produced in any numbers. The bent barrel attachments had very short lifespans – approx. 300 rounds for the 30° version, and 160 rounds for the 45° variant–as the barrel and bullets fired were put under great stress. Another problem besides the short life-span was that the bending caused the bullets to shatter and exit the barrel in multiple fragments, producing an unintended shotgun effect. As a result, weapons designers experimented with small vent holes drilled into the Krummlauf's barrel in order to reduce pressure and recoil, allowing the discharged bullets' built-up gases to be released to slow the bullet's velocity as it turned to exit the barrel. Nevertheless, the Krummlauf's lifespan remained the same. The 30° model was able to achieve a 35x35 cm grouping at 100m.

One of the biggest drawbacks of the small number (91 conversions) of Panzerjäger Tiger (P) casemate-type tank destroyers was that in spite of having a 88mm anti tank gun, the initial Ferdinand version of the Elefant did not have a forward-facing hull mount machine gun to handle enemy infantry. Hence, the Krummlauf was fitted with the Stg44 Gun and used by the tank crew as a machine gun.

Evidently the Russians tried to do what the Germans had done with the Sturmgewehr MP44 "Krummlauf" in order to be able to shoot around corners and was designed an experimental PPSh with curved barrel, Model 1945.

[Via 1, 2]