An "IZH 60 shema" typically refers to the or technical blueprint of the Baikal IZH-60 , a famous Russian spring-piston air rifle.

The buttstock can be extended by over an inch by moving a specific anchor screw shown in the assembly schematics.

The "shema" is essential for replacing the mainspring or piston seal, as the rifle's internal design is more compact and complex than standard break-barrel airguns. Key Features from the Diagram

Unlike break-barrels, the IZH-60 barrel stays fixed, which leads to better long-term accuracy because there is no hinge to wear out.

The rifle uses an 18mm front globe sight and a rear notch that can be moved along a dovetail to change the sight radius. IZH 60 Target Pro air rifle: Part 1 | Blog - Pyramyd AIR