The Dragunov SVD (Snayperskaya Vintovka Dragunova) is a Soviet-designed semi-automatic designated marksman rifle chambered in 7.62x54R, built to give infantry units precision fire between the range of a battle rifle and that of a dedicated sniper rifle. It uses a short-stroke gas piston and a milled receiver, and its standard PSO-1 optic carries a rangefinding reticle and a bullet-drop compensator. Most rifles sold in the United States under the Dragunov name are not SVDs. The Romanian PSL and the Serbian Zastava M91 share the cartridge, the general silhouette and the side-rail optic mount, but both are Kalashnikov designs: a long-stroke gas piston and a stamped receiver, in the PSL's case derived from the RPK light machine gun with a reinforced front trunnion. They are marksman rifles in their own right rather than copies. The practical consequence is that parts do not cross over. PSL, M91 and SVD magazines all hold ten rounds of the same cartridge and none of them interchange, and the same applies to most other major components.