Design-wise, the SKS relies on the AVS-36 (developed by the same designer, Simonov) to a point that some consider it a shortened AVS-36, stripped of select-fire capability and re-chambered for the 7.62×39mm cartridge. This viewpoint is problematic, as the AVS uses a sliding block bolt locking device, while the SKS employs a more reliable tilting-bolt design inherited from the PTRS-41, which was itself taken from SVT-40. The bolt mechanism is one of the defining features of a rifle, having a different bolt means the SKS and AVS merely appear similar in layout, while differing vastly in bolt lockup, caliber, size, and that one has a fixed magazine and the other has a detachable magazine. It also owes a debt to the M44, incorporating the carbine size and integral bayonet.