Getting more velocity out of 11.5" 5.56 - faster or slower burning powder?

[devldogs55]

Well I've got a 11.5" 5.56 that I enjoy plinking with, and I'm wanting to explore some different loads and get some more velocity out of this. Right now, I've got about 12 pounds of Ramshot TAC, but I don't know if I should go with something that burns slower like CFE223, or something a little faster like Ramshot XTerminator.

Below, I've posted the results of a load test I did with TAC, and I can get to 3,000fps, but it's not pretty. I'm sure there's a powder better suited to help me out here.

I took out 11 different loads using Ramshot TAC and 53gr Hornady A-Max in mixed LC brass and using CCI 400 primers. Each different load was a half a grain more than the last. I started with 24.5gr and went up all the way over max to 29.5gr. I didn't chose TAC for any particular reason other than I have a lot of it currently. Here's what I saw:

5.56 stamped chamber
11.5" barrel
1:7 twist
SilencerCo ASR Muzzle Brake
SilencerCo Omega with 5.56 end cap was mounted for all shots
COAL: 2.235"

Avg Velocities:

24.5gr TAC: 2498 fps

25.0gr TAC: 2553 fps

25.5gr TAC: 2625 fps

26.0gr TAC: 2753 fps

26.5gr TAC: 2813 fps

27.0gr TAC: 2844 fps

27.5gr TAC: 2875 fps

28.0gr TAC: 2951 fps

28.5gr TAC: 2973 fps *this is the first load where I saw pressure signs in the form of slightly cratered primers - but still is slightly under book max

29.0gr TAC: 3034 fps *this load is OVER book max, and primers were cratered still

29.5gr TAC: 3072 fps * this load is also OVER book max, and only one round was fired. The firing pin pierced the primer, and testing was discontinued.

 

[Yondering]

It's not about barrel length, but matching the burn rate and energy density to your bullet weight. With that said, in my experience X-Terminator (AA2230) gives a little higher velocity than TAC up to at least 65 gr bullets. With your 53gr A-Max, X-Terminator would be my first choice from the start, and I'd expect ~50-75 fps higher velocity when loading to similar pressure signs. In most cases I got better accuracy with X-Terminator as well.

If you aren't aware of it already, Ramshot / Western Powders load data has 5.56 loads for these powders, instead of just 223 Rem loads like most other data. I've found it to be fairly accurate data in my rifles, comparing where I stop at max loads vs the data.

See the flash when you shoot? That's a couple cents of powder burning outside the muzzle and doing you no good.

No, that is misleading and shows you don't understand internal ballistics or what causes flash.

 

[padom]

I run a 55VMAX with 25.4g H4895 in my 10.3" DD 1:7 SBR. It is extremely accurate also. Velocity is 2560.


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I am also getting similar accuracy with 23.3g 8208XBR with a Nosler 77cc out of my 10.5" WOA 1:7.