I just acquired an AK74 and it seems to not extract every so often. is this normal? I have been shooting .223 from it. was going to try 5.56X45 and see if it makes a difference. the barrel is chrome lined so cleaning is easy and stays squeaky. shot 60 rounds and jammed 4 times. maybe normal? this is my first "military" rifle so I'm new to the hiccups that may accompany them.