280ai build ?s

[Longshotjames]

I am looking at doing a 280ackley build. I am thinking of going with a Shilen 4groove ratchet rifling in 1:8twist for 175gr bullets

Do any 280ai owners suggest another barrel or rifling?

Also what angle does the ackley improved put the shoulder (30, 40deg) do different angle make a difference for accuracy, velocity or case life?

Thanks
James