Quote:
Originally Posted by Kale
S The 5.7 FN and 4.6 H&K rounds have a high speed and unusual light tip construction to encourage tumbling to make up for their small bore. T.
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This isn't accurate. The original 5.7mm round (the SS190) has a solid steel (density 8) tip in the shape of a cone and then a cylindrical body of aluminum (density 4) so it's a _heavy_ tipped design and not a light one. It's pretty much the opposite of how you'd design a bullet you wanted to tumble.
The HK 4.6mm is just one piece of solid steel. It's more likely to tumble than the SS190 but isn't really designed for it.
Because of their armor-piercing construction neether will fracture the way 5.56mm rounds are now known to do and much of the 5.56mm bullet's wounding power comes from this fragmentation and not just simple tumbling.
I can't find any real source for the tumbling wounding power of either the 5.7mm or the 4.6mm other than wishful thinking. The one time I've seen ballistic gelatin pictures for them there was just a simple non-tumbling wound channel that wasn't deep enough to meet FBI standards.
Their speeds aren't high by rifle standards either.