In case this hasn't already been posted...
In 2011, Barnes introduced a new LRX bullet designed to increase BC by altering ogive and boattail lengths (compared to their TTSX bullets) to improve long-range ballistic performance:
For 2012, Barnes has added a 6.5mm / .264 version weighing 127 grains. BC is .468 and SD is .260:
MidwayUSA website indicates that availability is expected later in March:
My guess is that these bullets will be somewhat long and take up excessive case capacity in the Grendel, but perhaps the higher BC might offset lower velocity to some degree.
Slightly off topic, but I'm still wishing for some premium 6.5mm hunting bullets in the 105gr to 115gr weight range with a good BC and reduced velocity needed for expansion (while still holding together for closer shots at higher impact velocities). Seems like this would be a sweet spot with the Grendel for medium game hunting, and a potential opportunity for bullet manufacturers.