Hell...Why not?
If I was to spec-out a custom barrel exactly how I would want one for my own personal 6.5 Grendel AR, here's how that would go down...
1) 5R cut-rifling
2) 1:8 RH twist
3) Stainless steel
4) Large Spiral Fluting both behind and in front of the gas block shelf
5) Rifle-length gas system
6) 20" finished-length
7) Bull-barrel contour with .936" gas block shelf
8) Rainier Arms Adjustable Bleed-Off .936" gas block
9) Rainier Arms Nitride-coated rifle-length gas tube.
10) 11º Recessed Target crown
11) 5/8-24 threaded muzzle w/ matching thread-protector