That number's probably pretty close from what I've experienced. HOWEVER, you'll want to watch for a vertical 'updraft' push from a tail wind blowing up slope(s) downrange.
You can usually see weeds flattening against hillsides downrange. Unless you catch the effect, it causes a change alot like a sudden boil - out the top!
BC of .750 at 3,150 huh? Sounds like your stuffin' some 7mm Cauterucios....???????
I'll order some 156's from Bob today and see how I do. I have a new barrel ordered for delivery around January one. Haven't decided whether it will be another 7 Dakota or a bigger seven. Are you satisfied with your RUM? Case quality ok? How many firings each? How long is your barrel to get 3400 with the 176's? What is your load? Group size?
If I go with a bigger seven should I stick with the 9 twist as you say yours works? Or if you had your choice would you go with an 8?