A friend of mine was shooting AK-47s in a shooting range in asia and he said it jams easily. Dunno how that fits in with "you can bury it for 10 years"
While on the whole the AK is somewhat prone to jamming, much of that is related to the fact that most AK-47s are made very cheaply in badly equipped workshops not exactly adhering to the strictest of engineering standards. The basic strength of the AK-47 is not so much that it is an amazing rifle, as the fact that it doesn't get any worse by constant abuse.
You can bury it for 10 years and afterwards, it will still jam easily.
That probably was a knock-off. I went through 6 months army training camp with one of those (the original), used it almost daily, and it did not jam once.