I have barreled several 6.5-284s with 8.5 twists and find it ideal for 140s including Bergers and 142 SMKs. My current barrel is 8 twist because that is what Shilen makes. I feel like I give up 30-50fps. Possibly could be the cut rifling makes the difference but it is there.

147 may well justify that extra 1/2".

NRA Benefactor Member

Those who live by the sword get shot by those who don't.