Hey guys, I am planning on building a 260AI platform with a pac nor barrel. It will be 26 inches with a 1:8 twist, my only predicament now is what type of rifling do I get? I can choose 3, 5, or polygonal. I plan on shooting 140 grain bullets which should stabilize fine with a 1:8, however I have the choice of 1:7 with the 5 groove. What would be my best option from these riflings?