NEW Hornady 6.5 Grendel 100gr ELD-VT Factory Load

[grayfox]

Measure the diameter of the base at the very bottom, then we can model the bullet in Grt.
That can lead to some comparative estimates and powders, etc.

[grayfox]

I can build an estimate with Acc 2520, at 2.280 OAL, that is very close to your observed MV, both 24" and 20" actual MV's.
2520 is a ball type.
So might be worth trying a ladder with it, start low, work up.
I was in the low 30 gr's, not the 25's. The limit, regardless of what OAL you can do, will be chamber pressure and seating length that has enough bearing surface resting in the case neck. That's why I stopped at 2.280. Maybe possible to get more but I think pressure is going to limit you there.
Don't try to "get" their powder it is a custom cannister blend, not what we can buy off the shelves.