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ALERT! Time To Update With More Ballistic Threat Levels!

(Courtesy of Hardened Structures) The Army is now fielding M855A1 ammunition for the entire line of 5.56mm platform weapon, for both magazine and belt fed weapons.
Ballistic Threat Levels Image
Everyone should become aware that these old established levels of protection no longer apply because of the M855A1 technology, and ballistic protection steel and concrete should now be enhanced by at least 100% until full testing and tables are established.
Quote From the American Rifleman article above:
"Fired from the M4's 14.5-inch barrel, the penetrator can pierce 3/8 inches hardened steel at 350 meters, "based on the range at which 50 percent of the rounds will pass through the barrier." That's more than twice as far as the earlier green-tipped cartridge's bullet and that distance is extended even farther when it is fired from the M16A2's 20-inch barrel. To test those claims, both were first fired into a hardened, 3/8-inch steel plate at 100 yards; the old M855's penetrator did not penetrate, leaving only a silver crater. The new bronze-tipped penetrator punched completely through. Next, the green-tip and bronze-tip bullets were fired at 3/8-inch soft steel at 300 yards. Again, the new bullet punched cleanly through, while the green-tipped M855 merely left a surface smear.
According to the Army, the new bullet also penetrates concrete blocks at 90 yards when fired from an M16A2's 20-inch barrel, and at 40 yards when fired from an M4's shorter barrel. A single green-tip projectile could not breach a concrete block at any distance."
Projectile technology is EVERYTHING to terminal barrier performance. And this level of M866A1 technology has raised the bar.
Last week I was testing barrier penetration against 8,000psi concrete pavers.
I wanted to test these because the 8,000psi rating is nearly triple strength of standard 3,000psi concrete for residential work, light commercial, sidewalks, etc.
The target media were 12" squares 1.25" thick.
The projectiles tested were:
  • 7.62 NATO standard Ball ammunition, 147gr FMJ at about 2,700 feet per second (FPS) from an 18" barrel
  • 8mm milspec ball ammunition from a 22" barrel
  • 300 Winchester magnum 150gr lead soft point at 3,100 FPS from a 22" barrel
  • Test distances were about 15 meters fired into stacks of 4 pavers thick.
The most powerful ammunition of these 3 is the .300 Win. Mag. by far, however the results on concrete were not played out in the real world.
.300 Win. Mag. shatters the first block and drives a clean hole through the paver leaving a neatly compacted concrete powder mound deposited on the second paver, (evidence the round was burrowing clean through) but never shattered the second paver.
The 7.62 NATO round consistently shatters 2 pavers thick. It does not leave the same neat deposits of finely compressed concrete powder anywhere but breaks through two 8,000psi pavers as though shattering glass.
8mm was surprising disappointing. It solidly shatters the first paver and inconsistently sometimes begins to crack the second paver. I was somehow expecting .30cal M2 AP level of performance from 8mm and see more damage. The 8mm was from two mil surplus lots, one Turkish, and one of unknown origin.
But the vast difference between "lesser" 7.62 NATO in FMJ outperforming the mighty .300 Win. Mag. is very noteworthy.
We can attribute this to the projectile.
Soft point lead hunting rounds are designed to transfer the projectile energy into the target. FMJ ammunition is a longstanding Hague convention standard of 1900 for international small arms, intended to result in "more humane" wounding.
With this new M855A1 5.56mm round into full production and good initial reports from "boots on the ground" the Army is now advancing into a new 7.62 NATO round based on this same technology.
We can also fully expect to see excellent barrier penetration from this new 7.62 projectile as 7.62NATO is roughly 200% the muzzle energy as 5.56mm
(note, on these same charts, down range the gap in performance of 5.56mm vs. 7.62mm widens to 928 ft/lbs for 7.62 vs. 268 ft/lbs for 5.56 at 500 meters)
In the design of Hardened Structures, we often reference standards for ballistic protection to satisfy threat protection levels.
One non-classified example follows:
Here we see UL level 7 is the 5.56 M193 round and requires 3/8" hardened armor plate and both .30cal M2 AP (.30-06 armor piercing to the layman) and 7.62NATO M61 (AP) require ½" hardened plate steel.
NOTICE: Everyone should become aware that these old established levels of protection no longer apply because of the M855A1 technology, and ballistic protection steel and concrete should now be enhanced by at least 100% until full testing and tables are established.

7.62×51mm NATO Rounds

New Military 6.5mm Creedmoor Rounds

"The U.S. Special Operations Command plans to begin fielding of the 6.5 Creedmoor cartridge in early 2019 to replace the 7.62 NATO round in semi-automatic sniper rifles. Tests determined that compared to the 7.62 NATO, the 6.5 Creedmoor doubles hit probability at 1,000 meters, increases effective range by nearly half, reduces wind drift by a third and has less recoil. The same rifles can use the new cartridge, as their similar dimensions allow the same magazines to be used and the weapon only requires a barrel change."

By Douglas Clark, AIA, NCARB
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