All I see is positive comments on the northfork and gs custom bullets with driving bands. I don't think I've ever seen a negative accuracy complaint. SO, not being a scientist I ask--does it have to do with less bearing area being pushed through the barrel at high pressure? Is it possible this reduces barrel whip?? Lets hear from you engineers!

I'm no engineer either, but it seems to me, if barrel harmonics were effected, it would be good for some rifles and bad for others, depending on barrel weight, stiffness, and length.

I think the accuracy of the North Fork bullets is simply a reflection of the quality control that Mike Brady exercises. These bullets have more bearing surface (or at least more resistance) than conventional hard alloy thin-jacketed bullets, which is why he urges users to reduce starting loads well below the usual starting load. I am an engineer but I can't give you an authoritative answer as to what effect a reduced bearing surface might have on barrel harmonics. I feel sure that it will have an effect, in the same respect that varying powder charges change the harmonics, but whether it will uniformly reduce the amplitude of the modes, I just can't judge. Its an intriguing question.

I think the driving bands reduce stiction in the barrel. Stiction is jerky motion caused by friction. I think this only important right after ignition, but I think it does explain why bullets with driving bands are more consistent in factory barrels than most bullets - and especially most monolithic bullets.

I think the reduced stiction allows very repeatable bullet acceleration, yielding repeatable "barrel harmonics" or "barrel whip" that is usually only achieved with custom barrels using normal bullets.

I wish I knew how to prove this!

Don