New IMI 5.56 Round, Armor-Piercing Match

[Kirk Freeman]

New primer? New way to load bullet into case?

Hmmm.

Israeli IMI Systems Develops Enhanced 5.56x45mm Ammunition Called 5.56APM - The Firearm BlogThe Firearm Blog

 

[Dean C.]

I wonder it it performs similarly to Big Greens new M855A1 , though after my own "redneck" ballistic testing for actual use I do agree with IMI heavier is the way to go with the 5.56 at this time.

 

[Hohn]

That's a wicked crimp on that thing.

 

[phylodog]

I want some

 

[Vigilant]

More accurate and better barrier performance than M80. Hmmm! Do want!

 

[KokomoDave]

IMI has some really nice Razor Core ammo too. I have some loaded in my 19X and and Tavor.

 

[AngryRooster]

I like the heavier round, it's a bonus that every round is fully tipped with sarcasm.

 

[T.Lex]

We've been running some 75gr for hunting hogs and deer in Texas with some really good results.

Yeah yeah yeah, I know that's like comparing apples and pineapples.

For this, though, could the crimp be stronger, or release in stages, such that the gas buildup is stronger? That'd be some tricky tolerances to keep the bolt locked long enough to create the additional energy.

 

[BiscuitsandGravy]

That's a wicked crimp on that thing.

Ditto on that. That is an interesting crimp. Sure would like to see a pressure curve vs. time.

 

[GIJEW]

It looks like there is a steel core that fits in the copper jacket kind of like a sabot

 

[AmmoManAaron]

I want some ASAP! That steel plate comparison really got my attention.

My WAGs:

- Tungsten cored.

- The new powder probably has a longer lasting and less sharp pressure peak.

- The firm crimp and new primer are related to the new powder and it's ignition characteristics.

- The firm crimp and new primer are aiding in the consistency of powder ignition and burn, yielding "match" type accuracy.

- The new primer is probably some type of magnum, perhaps even a new mix with a longer flame duration rather than just a larger quantity of typical primer mix.

There are two schools of thought on getting accuracy as it relates to crimping:
1.) Seat the bullet as close to the rifling as possible and with no, or minimal, crimp (minimizes bullet jump and avoids bullet deformation).
2.) When magazine considerations prevent #1, crimp the bullet very firmly which prevents the bullet from moving during the primer flash and delays the bullet movement until the powder is fully ignited. This second part (delaying bullet movement until the powder is fully ignited) goes back well over 100 years.

The new IMI ammo seems to follow school of thought #2 in regards to crimping.

Points to consider:

Long, long ago, match primers were made especially mild and match shooters in the U.S. essentially mixed thought #1 and the second part of #2 (minimal or no crimp and mild primer to prevent bullet movement during ignition). The old #0 primer comes to mind. The soft lead bullets of the time (hard cast wasn't really a thing yet, other than with big game hunters) were easily and badly deformed by a harsh crimp and thus a harsh crimp would negatively affect accuracy. This issue goes away if you have a bullet with a hard core and a copper jacket with a cannelure - like this new 5.56 APM ammo.

Schuetzen rifle shooters would breach-seat their bullets against the rifling (bullet telescopes into the case upon loading and closing the breach) and use a mild primer. Again, so that the bullet doesn't move until the powder is ignited and the powder does the work of moving the bullet. Mild crimp or no crimp doesn't work with a hard to light powder, plus there self-loading rifle and military handling considerations. The new powder means a hot primer and firm crimp are needed to get the stuff fully burning before the bullet moves.

Today, some BPCR shooters recognize the advantages of a mild primer and will add a tuft of tissue paper to slow down the primer flash so that the powder, once ignited, does more of the work of moving the bullet (aiding consistency). A new primer with a longer lasting flame, rather than just a larger dose of traditional priming mix, would be ideal for a new hard to light powder.

Some inline muzzleloader shooters using real BP will alter their ignition system from the 209 shotgun primer (very big and hot flash) to instead take a .25ACP case or cut down .22 hornet case with a small pistol primer. Without a crimp to hold the bullet in place, and the bullet already engraved from loading from the muzzle, primer flash intensity plays a big role.

Besides being cool, hopefully this new ammo helps bring back some of the old ideas about how accuracy can be obtained. These ideas are still alive in niche areas and are used with good results in those areas, but they are far from the mainstream even of most reloaders.

 

[Sling10mm]

Wouldn't that be banned for import because it could be used in a pistol? Similar to the whole 7N6 thing?

 

[AmmoManAaron]

Wouldn't that be banned for import because it could be used in a pistol? Similar to the whole 7N6 thing?

Depends on how the bullet is constructed. If the core is entirely tungsten or some other listed material, it is probably banned. If it is constructed like M855, which has combination core of steel and lead (steel in front, lead behind), then it should be legal for import. The entire 7N6 fiasco was classic gov't overreach and their interpretation is clearly wrong according to the letter of the law. I'm not sure if there is still litigation going on, as I have lost track of that particular issue.