Went out to the range today to re-zero the ACOG on my Bushmaster AK brake shorty. I also brought out my Maadi ARM AK to burn up some of the cheap Wolf 7.62X39 I have laying around. I loaded 5 rounds of Q3131 into the Bushy and proceeded to fire a 5 shot group, all 5 hovering around 1" to 1.5", looked good to me. I had some loose 5.56 rounds on the bench when I loaded up 10 rounds of 7.62X39 for the AK and proceeded to shoot at some clays out at the 100 yard mark, was squeezing off some AK rounds, bang, bang, bang, POP. I stopped, put the AK down and waited a good minute before I picked it back up, muzzle still downrange, and removed the 30 rd. mag. I slowly pulled the bolt back and could see the end of the "BRASS" shell casing. Holy F*#%, I just fired a 5.56 in the AK. I don't know what I was thinking when I was loading the mag, but I was talking with some other shooters when I was loading the mag and obviously wasn't paying attention. I took the cleaning rod and ran it down the barrel and the 5.56 casing came right out, ruptured in the middle of the case, fire formed to .30 cal in the mouth. No blown primer, the rear 1/2" of the case still the original diameter. Ran a patch through the bore of the AK, pulled it all apart, no barrel bulges, just alot of soot in the bore. Obviously the preasure in the chamber was quite low due to the .22 cal bullet and the .30 cal bore. I loaded up 1 round of 7.62X39 and squeezed off a round, went and recovered the empty, looked perfect. I shot another 100 rds. through the AK after that, no problems noted. I just think how lucky I was not to have an AK bolt imbedded in my forehead! My stupid mistake but it just goes to show that when you get distracted such things do happen. My motto has always been "It's better to be saftey concious than to be unconcious"