That may true of a new pristine rifle barrel. But what about an AK-47 that that has had a few thousand rounds poured through it already? That rifling you speak of may become nearly non-existent. May be enough left to make it go fairly straight, but the spin to keep it from tumbling will not do that job anymore. And I don't think these folks worry too much about the condition of their gun barrels either.
Don
http://www.fen-net.de/norbert.arnoldi/army/wound.html
<snip>Yugoslav 7.62x39mm - The Yugoslav copper-jacketed, lead-core, flat-base bullet, even when fired from the same Kalashnikov assault rifle, acts very differently in tissue. It typically travels point-forward for only about 9cm before yawing. Due to the lead core, this bullet flattens somewhat as it yaws, squeezing a few small lead fragments out at its open base, but this does not add significantly to its wounding potential. Referring to the wound profile of the Soviet AK-47 bullet (Fig. 2) and blotting out the first 17cm of the projectile path will leave a good approximation of what one might expect from this bullet.
Since this bullet would be travelling sideways through most of its path in an abdominal wound, it would be expected to cut a swath over three times the dimension made by the bullet travelling point forward. In addition to the larger hole in organs from the sideways-travelling bullet, the tissue surrounding the bullet path will be stretched considerably from temporary cavitation. Actual damage from the stretch of cavitation can vary from an almost explosive effect, widely splitting a solid organ such as the liver, or a hollow one such as the bladder if it is full at the time it is hit, to almost no observable effect if the hollow organs (such as intestines) when hit contain little liquid and/or air. The exit wound may be punctate or oblong, depending on the bullet's orientation as it struck the abdominal wall at the exit point. The exit wound could be stellate if sufficient wounding potential remains at this point on the bullet path. The thigh entrance wound will be small and punctate but the exit wound will probably be stellate, measuring up to 11 cm from the tips of opposing splits. The stellate exit wound results from the temporary cavity simply stretching the skin beyond its breaking point. These stellate wounds generally bleed very little. Small-to medium-sized vessels are certainly cut or torn, but the temporary cavity tearing action generally stimulates the tiny muscles in the vessel walls to constrict and clots will form in their open ends, limiting blood loss. Being wide open, these wounds tend to drain and heal amazingly well even in situations of limited surgical resources. This increased tissue disruption of the leg will, of course, temporarily limit the mobility of the person hit to a greater extent than wounds causing less tissue disruption.
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