I was thinking a more heavier starting profile fluted down to about the weight of a 3b
Right, yeah the argument is that all things being equal the fluted barrel will have less deflection that a non fluted barrel of equal weight... Gun smiths as well as barrel makers are split on this subject.
The rabbit hole is strong with this one. Some people lean on the I Beam effect and corrugated geometry of the "correct fluting".
Geometry (Spiral, straight (would make the most sense to me), 3 flutes vs 6, Hex pattern...ect and then depths and radius on all of the above, how much stock you end up with between your flutes and the bore wall... the list of variables goes on and on.
Others on the against school lean on mechanical elastic modulus of material removal. I think this is one of those no right approach deals where there is no straight answer.
Going back to the actual question, if the end goal is to have a NRL hunter legal gun under 12# i dont think fluting will make that much of a difference. Ive shot a handful of these and most guys are running 3Bs and light/medium palmas when not running Carbon wrapped.
22"-24" will get you over the 380K points for power factor with a 140 in 6.5 or 135 in 25. and almost no one runs shorter than 22" on the short cartridges