How could or should the 6.5 mm Grendel be improved?

[SHORT-N-SASSY]

We only made 50 PPC size bolts for 1 small batch of barrels. They are being used but we don't hear much unless something goes wrong. None have broken on the PPC size or BR size.
I still have the first 6BRX I made in 09. 36 gr of N550 will push a 95gr SMK to apx 3200fps.

Woohoo,

How would you compare the AR Performance 800 Series .30 Rem AR bolt & extension set, with Remington's Bolt-Barrel Extension design used in their R-15 .30 Remington AR rifle? Which of these two designs has the larger Bolt circle diameter and Barrel Extension diameter? And, other than diameter, does one design offer more than the other?

I'd like to see a side-by-side comparison test. My personal thought: these designs open up a whole new ball game for the AR-15 platform.