Before you make your purchase, especially if it's your first SKS, or first rifle, you want to know if it is in a legal semi-auto configuration, or if someone has modified it to function in an illegal full-auto mode. We all know "any" semi can be converted, and over the years we have noticed several different versions of this unwise conversion with the SKS. Some are easy to distinguish, with a screw sticking up through the bottom of the tr guard, but others cannot be distinguished with a cursory looking over. But here's an easy way to test it. (applies to most semi-autos)
It's wise to ask a seller's permission first, of course, because it involves dry-firing it twice. Be Sure there is no ammo in the gun, cycle the action to assure the hammer is cocked, squeeze and Hold the trigger back when you dry fire and do Not let the trigger return to its forward position. While continuing to hold the trigger back, cycle the action and be sure the carrier comes fully to the rear, and then fully closes. Now, release the trigger and pull it again. If you get the "click" of the hammer falling, it is semi-auto, but if pulling the trigger the second time results in nothing happening, the hammer has "followed" and you need to avoid this illegal example of an otherwise fine firearm.
It seems to be easier to do the test left handed, as you don't have to cross your arms to manually cycle the action while holding trigger back.
Just in case you're thinking of making seller a cheap offer for his "illegal" gun, be advised that in the eyes of the ATF, once one has been converted to FA, it can never be "legally" converted back to SA.
