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FirstFreedom · March 24, 2005, 04:52 PM

My .02 based on my limited understanding:

1. The .mil does not want to penetrate steel; they want to penetrate kevlar helmets and kevlar vests of the enemy at a given distance, be it 300, 400, 500, or 600 yards. We can argue about whether or not that is worth the tradeoff of violent expansion and tumbling at close range; but let's understand the true goal of the penetrator rounds.

2. The *exact same dynamic* that makes a bullet cut through the air due to its high BC/sectional density, giving it more downrange retained energy is the dynamic, coupled with speed, that makes it penetrate the enemy's vest/helmet at all ranges, but particularly at the longer ranges. Therefore, the 6.5 grendel not only has the best downrange trajectory and retained energy of the rounds mentioned (somewhat important), it ALSO has the best penetrating ability at all ranges (more important); yes, superior to the .308 even, given equal bullet speed. At a given speed and given bullet shape & contruction, it's all about sectional density. But this only matters at very long ranges, cuz ALL of these pop through helmets at shorter ranges easily.

3. My opinion is that in a light rifle, the .223 is fine with proper bullet choice, but the 7.62x39 is better still; the 6.8 spc is better still; the 6.5 grendel is better still, and something in .257 or 6mm would be even better still, because it would give the BC and penetrating ability of the 6.5, with the higher velocity, closer to the .223. That's the sweet spot for a full auto assault rifle, IMO, not 6.5 or .277, not .223. 6.5 is getting very close however - it's a nice tradeoff if you're a believer that a lot of enemy will catch random un-aimed small arms flak at very very long ranges, where .223 might bounce off the flak jacket; 6.5 grendel certainly wouldn't (talking looooong range though - 600 plus). It would actually penetrate BETTER than a .308 at that kind of range, with less gun weight, ammo weight, and recoil.

March 24, 2005, 04:52 PM	#17
FirstFreedom Junior member Join Date: May 31, 2004 Location: The Toll Road State, U.S.A. Posts: 12,451	My .02 based on my limited understanding: 1. The .mil does not want to penetrate steel; they want to penetrate kevlar helmets and kevlar vests of the enemy at a given distance, be it 300, 400, 500, or 600 yards. We can argue about whether or not that is worth the tradeoff of violent expansion and tumbling at close range; but let's understand the true goal of the penetrator rounds. 2. The exact same dynamic that makes a bullet cut through the air due to its high BC/sectional density, giving it more downrange retained energy is the dynamic, coupled with speed, that makes it penetrate the enemy's vest/helmet at all ranges, but particularly at the longer ranges. Therefore, the 6.5 grendel not only has the best downrange trajectory and retained energy of the rounds mentioned (somewhat important), it ALSO has the best penetrating ability at all ranges (more important); yes, superior to the .308 even, given equal bullet speed. At a given speed and given bullet shape & contruction, it's all about sectional density. But this only matters at very long ranges, cuz ALL of these pop through helmets at shorter ranges easily. 3. My opinion is that in a light rifle, the .223 is fine with proper bullet choice, but the 7.62x39 is better still; the 6.8 spc is better still; the 6.5 grendel is better still, and something in .257 or 6mm would be even better still, because it would give the BC and penetrating ability of the 6.5, with the higher velocity, closer to the .223. That's the sweet spot for a full auto assault rifle, IMO, not 6.5 or .277, not .223. 6.5 is getting very close however - it's a nice tradeoff if you're a believer that a lot of enemy will catch random un-aimed small arms flak at very very long ranges, where .223 might bounce off the flak jacket; 6.5 grendel certainly wouldn't (talking looooong range though - 600 plus). It would actually penetrate BETTER than a .308 at that kind of range, with less gun weight, ammo weight, and recoil.