Page "SVT-40" Paragraph 3

The SVT-38 is a gas-operated weapon with a short-stroke, spring-loaded piston above the barrel and a tilting bolt.

Thus it became one of the pioneers of this configuration, which eventually became widely used.

There is some dispute about who exactly first developed this operating principle, as the SVT's mechanism ( as implemented in 1935 competition prototype ) closely resembles Dieudonné Saive's design of 1937 ; Saive eventually designed the FN FAL, which employs the same operating principle as the SVT.