Like I said, IQ test fail! Don't slam a collapsible stock on the ground with it extended! Don't do it with your finger under it! I know its common practice and have done it myself (with a fixed stock). I won't have to use it anymore though now that I'm sticking to AK's!That is a common practice to clear malfuctions when the charging handle isn't enough. Maybe next time he will remember to collapse the stock first. I have used this technique many times.