Ok.  After about 2 years of thoroughly testing almost every reasonable 5.56 powder you can buy on the market, we made some summaries, so you can get a good idea what powder will work for what you want to do...

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How much velocity did we get with what powder charge?
Take a look at the grid.  These are 55 grain bullets, and what charge yielded what velocity with a 20" WOA barrel.  Sometimes the powder charge is same or less and it is showing more velocity.  This is because this is across ALL loads we shot, some were winter, some were summer, and also case capacity varies from lot to lot. 

16" Proof Research Carbon Fiber Barrel & WOA 20" 

Charge weights are in the grid, velocity is shown at top, powder on left.

75-77 Grain Bullets
The 75 Grain are Hornady BTHP, the 77 Are Berger OTM generally, and some SMK 77

Inside the grid is CHARGE WEIGHTS that yelded velocity shown on top, with what powder.  To give you an idea.  Depending on whether or not these were shot in winter or summer, or with different case capacity, is why you see sometimes lower value giving higher velocity, etc.
Berger Match Bullets & 77 OTM
Berger is what we think is the most accurate bullet of what we ever tested.
MOA:  Sierra Match king, BlitzKing and some Barnes TSX/TTSX/GMX
We can see here, N133 is pretty much top tier for light bullets.
Standard Deviation
These are averages across several loads with these type of bullets, and different charges, so you can see an example of how a powder trends, if you load it precisely. 
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