I have a 9 twist 24" shilen and it shoots great. But I saw the velocity on the 20" barrels and will likely go with a 20" Blackhole weaponry standard profile barrel. It's a nice compromise for a carry rifle in an ar15 setup. I have that profile on a 6x6.8 bhw. I always lean toward the fastest twists on my barrels now. Never know what grain bullet you may end up choosing. Or those Excalibur barrels have caught my attention lately, so I've been wanting to try one of those also. Always something, but a 10 twist is the slowest I'd go in a 204