Dan,
What I'm wondering is why some would question whether a 250-grain, flat-based spitzer won't stabilize in a 1-16 twist. Remington's standard twist in the .350 Magnum was 1-16, and one of their original factory loads featured the 250 Pointed Soft-Point Corelokt. For some reason they changed that to a round-nose when they introduced the .35 Whelen as a factory load, but they stuck to a 1-16 twist, and a lot of handloaders used 250 spitzers without problems.
Maybe it has to do with the persistent belief that muzzle velocity has a vast effect on bullet stability, to the point where a certain bullet will shoot inaccurately at a certain velocity, or even tumble, yet will stabilize when pushed 100 fps faster. While extra velocity does have a slight effect, it's far less than the effect of temperature or altitude.
Another item I wanted to mention was that the Berger program works best with boattail spitzers, especially those with very high BC's. It isn't as accurate with flat-base spitzers, though quite often they stabilize easier, due to more drag on the flat base. The Berger program also doesn't account for the fact that the length of plastic tips doesn't "count" nearly as much in overall bullet length, due to the very light weight of the tips. Which is why some varmint shooters believe the 40-grain Hornady V-Max is too long for the .204 Ruger's standard 1-12 twist--which is actually plenty. The JBM twist program has a place to note the length of a plastic tip, so is more accurate with those bullets.
