#Mk262

We shoot 5.56mm IMI 77gr OTM ammunition from an AR15.com AR15 with a 10.5″ 1:7″ twist barrel into Clearballistics ballistic gel to measure velocity, penetration, expansion/fragmentation, and retained weight.

The first round up of the Big Freakin’ Cartridge Test is IMI’s take on the Black Hill’s classic heavy precision load, Mk. 262. Branded as “77gr Razor Core”, IMI’s version sports annealed 5.56mm NATO cases, neck and primer sealant, and of course 77gr Open Tip Match projectiles. Continuing on from the first installment, we are now looking at the velocity test results for the 16.1″ and 20″ barrels. The test procedure was as follows:

The first round up for the Big Freakin’ Cartridge Test is IMI’s take on the Black Hill’s classic heavy precision load, Mk. 262. Branded as “77gr Razor Core”, IMI’s version sports annealed 5.56mm NATO cases, neck and primer sealant, and of course 77gr Open Tip Match projectiles. Based on reputation alone, I expected the best accuracy and relatively high muzzle velocities from this ammunition. The test procedure was as follows:

“Nathaniel’s starting another series? Oh brother…”

The United States House of Representatives has ordered trials to be conducted to determine the right ammunition for both the US Army and Marine Corps, following on the recent controversy that each service was using its own unique round. Army Times reports:

Over at WeaponsMan, Hognose broaches the subject of “OTMs” and “JHPs” and that they are not the same thing. He writes:

The 5.56mm M855 round has received considerable criticism for its terminal characteristics. Detractors point out that the round fails to fragment when the striking velocity is too low – such as when fired from a very short barrel or when the bullet has slowed down thanks to its relatively unimpressive ogive shape – or when the bullet strikes the target at a very low angle of attack.

In response to the ongoing dustup over M855 ammunition, Ian and Karl of InRange TV have done a short video explaining some basics about the round, and its capabilities. As host website Full30 does not allow videos to be embedded on other websites, readers will have to follow the hyperlink to watch the video.