What kind of accuracy can one expect out of a 24" heavy freefloated barrel?

The barrel is one of the many equations of the formula.

With the new barrel, you need to head space the bolt via the locking shoulder, then make sure that the lower/upper are locking up tight.  Getting the trigger down below the 3lb mark with no creep is a must. Changing out the sights to a match style helps by miles; the front spun filed to reduce the width, and the rear changed out to a hooded .030 peep. Checking the gas piston for clean movement (not bent or out of round) is a step in the right direction too.  And, the most important item, working up loads that make the rifle/barrel harmonics sing.

If your planning on just spinning a new barrel on, then go shoot, you may have wasted money.  If you plan on building a match rifle (not legal in the CMP shoots) up to it’s potential (including loads), expect around .60/.70 MOA (5 shot groups) on a good day.