7.62x51 M1A F-C 11 disected a round

[swampratt]

Friend gave me one of these .308 rounds that came in a link belt or something.
I pulled the round and weighed it, the projectile weighs 168gr
and is a HPBT.
The powder...GET THIS
I got some new IMR4064 circa 2012 and it looked different..long sticks and short sticks and some flake ball looking stuff in it..

Well that is what was in this !
Now i weighed it 44.5gr.
I heard someone say the reason for the changed in 4064 powder was to meet mil spec or making it for the military rounds...

I figured maybe, maybe not.
But it is in fact in this ammo

I forgot to measure OAL,, so i did it after pulling the round and came up with 2.810"

will get a few more and measure the force to pull the bullet.
The bullet is sealed in with black sealant ...

The bullet has scratches on it after being removed with inertia puller...So brass is not that super smooth neck stuff...

May shoot a few to see what they do.

Some more measurements:
Brass length 2.007"
Brass weight 175.1 gr
Removed primer and it is light green inside.
Have fun be safe..

 

[Blitzfike]

Interested in what you learn here. I've been loading my 308's with a surplus commercial canister powder that I get from a guy in Tennessee. I've had to work up loads for it with a chronograph, but so far it is working well for me. A couple of places I buy reloading supplies from sell pull down powder from military loads when they can get it. How does the 44.5 grains weight charge compare with published load data for the IMR4064? Thanks.. Blitzfike

 

[ASP785]

Swamp,

This is my hypothesis. The government was looking for an accurate, flash suppressed temperature stable cartridge. They turned to Federal Cartridge Company to create the MK316 round. The first article states that a "modified extruded powder" was used in the creation of this cartridge. The original MSDS of IMR4064 lists potassium sulfate, a flash suppressant, as an ingredient. "Complete temperature stability can only be achieved with tubular extruded powders designs, either with double base (NG) and/or with other coating technologies." If we could determine whether the new batch of IMR4064 had nitroglycerin now added, we might get somewhere. Since IMR won't answer why the change, I can only continue to guess, but if you improved the powder for the military, why not offer it to the public. Considering this is one of the only popular powders to have changed formulas, at least in a physical appearance sense, then I believe it could be plausible.

Goals of MK 316 ammunition:
http://www.dtic.mil/ndia/2009infantrysmallarms/tuesdaysessioniii8524.pdf

http://www.snipercentral.com/m118.phtml

 

[swampratt]

That powder load is .5gr under max load in the lyman 49Th
the OAL of the round is .010" less than max in the book

That powder is a dead ringer for the new 4064...same size granuals and same small ball flake looking things and same exact color and sheen.
The old 4064 has a different VMD (Volume measured density)
The old 4064 also has different fps when the loads are weighed vs the new.

I have no idea about the nitroglycerin though.