Using 55 grain bullets, you can see the 27 grain load was actually very similar velocity.

Moving onto the 77 grain Sierra Match King, we can see that StaBALL Match is "perhaps" a slower burning powder, or for sure, it requires MORE powder to achieve same velocity.  Which Accurate 2520 is highest velocity, but SW Match Rifle is VERY similar to it. 

We didn't load up the SW Match Rifle with the Berger 77 OTM's, but damn, the Accurate 2520, to shoot 5 shots through that small .4" hole is quite good.  What is disappointing is that I didn't have a stable foundation at the range, the crosshairs were not so steady on the wood block...and I pulled the last shot to the right on that StaBALL 25.2 grain with the Berger OTM's.  I think it would be a similar group to the Accurate, or about .5-.6" at least. 

Several groups at an inch, and some less.  Bullets used:

Berger 55 grain Varmint

Sierra 77 Grain MatchKing

Berger 77 Grain OTM

Accurate 2520 wins this round...in terms of accuracy and velocity.  But all three powders are similar.