There are two things that will jam an Ak from my "hands on" experience. First is of course packing grease. Thats right. When you first get you shinny new AK it has to be cleaned! Who'd of thought. Second way is the one that stumped me for a while. My AK is the YugoM70a2 model with grenade launcher site. After firing the weapon for the first time, after about a 100 shots i noticed a little nut coming loose on the gas block section. I hand tighten it back down of course. Then the weapon started jamming because the bolt was not getting charged all the way back. Thinking there was a million other problems, i cleaned everything, bought every type of ammo i could get my hands on, consulted a Vietnam vet who was a green beret...did everything i could to no avail. Finally i started trying to put goo gone down the gas block thinking something was in there. (i didnt have a pipe cleaner) Then i noticed that when i flipped the grenade launcher(gl) sites, the little bolt that holds the gl in place had a groove cut through the middle of it and i could see that it was blocking the hole when the bolt was traversed. I moved it around some. Test fired. No good. Then i grew a brain and i noticed on the side of the gas block that the bolt has to line up exactly with the cut out pattern of the bolt holder. Brilliant! Works like a charm now. Funny how things work better when they are put together right.