To add to this discussion:
AK-47 and variants have significant upward recoil when fired in burst or full automatic mode. You can control it in burst and even full automatic mode, but you have to know what you're doing and it's physically demanding due to the way you have to put downward pressure on the gun with your arms and practically hunch over it so you can get additional control with your body. Done correctly, putting 7 or 8 out bullets out of a 10 round burst on a stationary man-sized target in full automatic mode is completely possible.
As far as ammo forming lines, if you use tracer rounds, yes, they most certainly do. Having been on the firing range at night time with two platoons shooting tracer rounds while two watched from the sidelines, it was quite the light show. If you put every third, fourth or fifth round a tracer, it will indeed cause a lot of lines to be seen when firing in swift succession single shots, burst fire or full automatic.