FMJ yaw and upset performance

[Tony Williams]

There was one Nato country that deliberately used a very brittle 7.62x51 bullet and jacket design that was made to tumble shortly after entry, and break in half at the cannelure. Then there were at least two bullet fragments making at least two wound channels. This could also be done with a 6.5mm bullet.

As long as the money was available for research, I don't see any reason why a bullet couldn't be made with two cannelure type indentations so it would break into three pieces each weighing around 40 grains.

The German ball bullet fragmented violently, but I'm not clear whether this was deliberate or accidental.

The problem is that the "Geneva legal" requirement excludes fragmentation (the British 5.56mm L2A2 ball has a thicker jacket than the original L2A1, specifically to reduce the probability of fragmentation).

Which is why I'm so concerned that the bullet must yaw rapidly on impact. If it just punches a neat hole straight through, then the effectiveness will be limited unless it hits something vital. If it yaws rapidly and travels sideways through much of the body it will tear a much bigger wound channel, giving a greater chance of hitting something vital or of rupturing enough blood vessels to cause more rapid bleed-out. A long, low-drag bullet will tear a bigger wound than a short one when it's sideways, which in an intermediate calibre would compensate to some extent for the reduction in calibre and mass (the 123 grain 6.5mm Lapua is longer than the 7.62mm M80).