Ya man. Like...sure.
Selecting a barrel is like buying boots for a fairly specific sport. Everyone's foot is different and boot makers use different lasts. When you try in a ski boot, climbing shoe, or mountaineering boot for the first time and an experienced person is helping you, they generally ask, "How does it feel? Is it too tight? Or too loose?" At this point it's like asking a virgin what sex feels like. No clue.
In all reality, it's just going to take your own gained experience through failure to develop personal preference. So full send on the first thing you think is right. And start learning.
Here's what I will say. Don't get fixated in a specific brand. Bartlein, Krieger, Mullerworks, Brux, Proof.... they're all going to outshoot you. You won't be able to tell the difference in performance for a long time. It's like someone who's never ridden a motorcycle jump on a KTm and try to point it's flaws out.
Contour. Has more to do with what discipline you're participating in and what the rest of the rifle components are? Are you trying to achieve a certain weight? Can your chassis or stock accept weight kits? Are you okay very much limiting your rifle to a 50yd tether from the back of your car?
And yeah, 7 twist in a 6.5 is for very long bullets and low altitudes. Traditional is 8 twist. 7.5 probably gets all cup and core bullets stable with good BCs at all altitudes with both 6.5 CM and magnum bolt faces like PRC. The good news with this soec is that it's fairly objective. Just visit the Berger stability calculator. This is not a case of P for plenty is mo betta. Use the minimum twist that gets your bullet stable with a decent BC. More RPMs can blow bullets up if you push them fast enough. Although that's not too likely with a 153. And a Berger.
