4 Reasons why review is awful
1. Discusses the potential of the rounds, rather than the reality. The 6.8mm Remington at the muzzle has a 7.45 gram cartridge traveling at 785 m/s, or generates 2300 joules, from a 16 inch barrel. By comparison from a 16 inch barrel the 5.56mm produces 1,600 joules with, at the very largest, a 5 gram bullet, and on average 3.6-4.1 grams. From a 24 inch barrel, the 6.8mm Remington produces nearly 2700, compared to the 1800 for the 5.56mm. Even if a 5.56mm had more in "potential", that doesn't make the reality of the situation, based on real life not theory, completely different.
2. He discusses the bullet drop, which is identical to the Mk. 262, despite being a larger, heavier round, which means that the idea that bullet drop is a considerable problem, when we're talking 2 inches compared to 3 inches, which is insignificant in it's own right, is just plain silly. There's no relevance here; most sniper rounds due have slightly more drop, and it's irrelevant.
3. He talks about the lethal velocity of the 6.8mm Remington dropping off before the .223. The problem with his argument is that the 6.8mm Remington stays lethal, for longer. In fact, the .308 also has a lower velocity, but a longer lethal range according to the military. The tiny 4.1 gram bullet loses energy rapidly and has to maintain a certain velocity to retain it's fragmenting capabilities in order to be lethal. The bigger, heavier bullet of the 6.8mm Remington stays lethal longer, has a different lethal velocity, and doesn't rely on fragmentation, which means it's effective range is drastically greater than the 5.56mm. Him comparing what the .223 needs to have and saying the 6.8mm Remington doesn't meet that completely misses the point.
4. The BC, or ballistic coefficient of the best, 5 gram Mk. 262 round is about .36, which is identical to the average for the 6.8mm Remington. Both cartridges also get about 1 MOA. In comparison the average .223 gets about 2-3 MOA and has a BC of about .2. Basically, BC means that a round has lower aerodynamics and efficiency, and thus loses energy more rapidly at longer ranges.
The 6.8mm Remington is not the best cartridge ever due to it's lower ballistic coefficient than similiar rounds, such as the 6.5mm Grendel or .280 British. However it's primary advantage doesn't lay in terminal ballistics, but rather superior performance from shorter barrels. It's effective range is nearly 500 meters, out of an M4 carbine, compared to about 150 meters for the 5.56mm. This is according to the U.S. military. But Joe Blow on the internet using incorrect figures for what he's talking about, he's got it right.
