The SVN (Snajperskaja Vintovka Nikonova) it's a performing battele rifle that use the Nikonov "blowback shifted pulse" mechanism that permit to fire 2 round bursts at the devastating ROF of 1800 RPM
This Battle rifle use the 7.62 x 54mm Russian rounds using the same mags of the SVD but are also avabile extended 20 round mags the strong recoil during the hi-speed bursts is absorbed by springs and rubber shock absorbers inside the stock

Caliber: 7.62 x 54mm Russian
Mag: 20 (or SVD 10 round ones)
ROF: 1800 RPM 2 round bursts then 550 RPM full auto