Soda Pop

Anyone know what it is?

I know the bullet is a Sierra 77gr HPBT, but what is the powder and charge?

Daniel Watters

The only folks who know for certain work for NSWC-Crane or Black Hills Ammunition.

Charlie Petty

Pop, even if we knew the information would be useless since they are almost surely using a non cannister powder we couldn't get anyhow.

My understanding is that lots of people are using Ramshot TAC for loads like that and their load guide has data for the Sierra 69, Hornady 75, Nosler 77 and Sierra 80

Soda Pop

I didn't know it was that much of a secret. I think it's common knowledge that the M855 is 26.1gr of WC844.

Charlie Petty

I don't know that there is any secret involved but rather that there are so many small variations in commercial powders that you cannot specify a charge weight down to the nearest tenth. In the factories they are able to compensate for differences between one keg... or carload... of powder and the next.

Sunray

"...they are able to compensate for differences between..." Yep. Every powder lot is slightly different. Factory ammo is loaded to give the velocity and accuracy required by the specs. The exact powder charge can vary between lots. One lot of M855 may have 26.1 grains, but not necessarily all lots.

threefeathers

i duplicated the velocity from my 20 inch Colt 1-7 barrel with 24.5 grains of Varget driving the Nosler 77 grain with cannelure.

Kevin Gibson

The military doesn't spec a charge weight, they spec the performance. Pressure, velocity etc. Your best bet is to pick up some Ramshot TAC (which is the catz-arse) as Charlie said and work up to the desired performance level.

Soda Pop

Source?

Charlie Petty

Due to hazmat shipping it is best to find a local source... if not Midway, Wideners, Grafs and many others

threefeathers

I love TAC but I was not able to get the velocity in my M262 clones with it. I began blowing primers. I've tested the hell out of this, I was able to use issue M262 as a base and chrono it. TAC did approach it, TAC is perfect for M855 loads, it is fantastic for match loads in with 73 grain Berger bullets and 77 grain match loads. But in my tests it is pushed for the really hot m262.

The powders i used that chroned exactly what M262 chronoed were Varget which I have already given and N540. Seveal other folks have used RE15 but I haven't been able to test it yet.

Given that a match load doesn't need to be the most powerful load.
I'd love to see other folks data using TAC. Understand I buy it in the 8 lb jugs.

Kevin Gibson

Military 5.56 tends to have high pressure, so I’m not surprised at your experience with TAC. The reason I recommend TAC is because it’s such a user friendly powder. It meters well, it gives very consistent velocities, shoots clean and is not very sensitive to environmental changes. Actually, one could say that for most of the Ramshot powders, which are quickly becoming my favorites.

threefeathers

Don't get me wrong, I love TAC and will use it in the vast majority of my loads. I just started to ge blown primers with the 77 grain pill when it hit 2800+ fps from a 20 inch barrel.
With Berger 73 grain it is a shootin' honey. I will make more of this than the M262 clones.

Now, the next round I'm experimenting with is the solid copper M292 or whatever they're calling the brown paint dipped bullet.

Alaska338

Black hills were the first to contractor to start the MK 262 program for the MK12 rifle.

TAC was base powder but was blended due to flash spec.

Bullets used were Nosler 77gr and Sierra MK without crimp and the last version with crimp grove. MK 262 mod 1.

IMR 8208 is used at 23.8
In the 18" Douglas Barrel 1/7 it will be the 2748 FPS.
And burns very clean in my MK 12
I use Lee factory Crimp Die and FC 09 military brass

Probably the best 5.56 defensive round ever.

William R. Moore

I've had very good results with heavy bullets in .223/5.56 with both RE/RL15 and AR Comp and Remington 7 1/2 primers. It does help to load a little long but still fit in the magazine.

You also might want to consider trying the Federal #41 primer, it's the mil-spec primer for use in 5.56 x 45mm. Allegedly, a slightly harder cup. However, before you get all enthused about matching M262 mod?, please recall that Uncle Sam is covered by sovereign immunity from lawsuits resulting from excessive pressures. Black Hills will not release their super duper .300 WM load outside military procurement channels. Sometimes, close enough for government work is a good motto.