All bullets have a bit of yaw when they leave the barrel, but the amount is minisule, as in fractions of 1 degree. Faster twists may exacerbate bullet imbalance, but these manifestations are of small import regarding angular momentum and aerodynamic moments. Keep in mind that when a bullet strikes a target, flesh or other, that the medium that is transited renders these issues to insignificance.
There are two primary modes of precession for gyroscopically stabilized projectiles, one fast and the other slow. They coexist initially in the form of an epicyclic precession that resembles a rossette pattern, with the fast cycle making the smaller and more frequent loops about the bullet's yaw axis. Over the course of flight the fast cycle precession typically nulls within 200 yards. The slow cycle responds as a function of gyroscopic stability factor, that is, if the GSF is low the yaw may remain constant, or grow smaller under the influence of a high GSF. If my understanding of these issues is correct, the slow cycle precession is a function of projectile imbalance, the fast cycle one of projectile or aerodynamic jump. In any case, the complete cycle of a single precession occurs over the course of 50 yards or so, and the amount of yaw that is creates is VERY SMALL, even in extreme cases.
Now how this relates to fast twist/slow twist comparisons is somewhat of an 'angels on the head of a pin' discussion. What stabilizes a bullet is angular momentum. Longer bullets require a faster twist for a given caliber, but what is required ultimately is enough stability to overcome the aerodynamic overturning moments that result from the difference between the Center of Aerodynamic Pressure(CP) and Center of Gravity(CG) of the projectile. Larger diameter projectiles generally require slower twists to achieve this stability because the greater radius provides equivalent momentum at a lower angular velocity. So, what does this have to do with your question? The issue is one of stability, and that is one of bullet length and twist rates as required to provide same in the atmosphere. All of these issue pale to insignificance in the density of flesh and bone, and where the speed of sound may exceed 4000 fps. All bets are off. There are shapes that have an excellent history of boring straight through a heavy beast, and they are primarily round nose solids or FMJ's that do not deform. There are shapes notorious for wandering off course such as the boat tail soft points. What is certain is that if the bullet changes shape there are issues at play that are of greater influence than whether the bullet rotates once as opposed to twice as it transits the beasty. Unequal expansion, bone strike, core separation to name a few.
Try this site when you have some time to kill:
http://www.mindspring.com/~ulfhere/ballistics/wounding.htmlTry these books for good info on exterior ballistics and other esoteric discussion: "Rifle Accuracy Facts", by Harold Vaughn and "Modern Exterior Ballistics", by Robert McCoy.
Check out Vaughn's book first, and if you find it interesting and are somewhat less than intimidated by math, go for McCoy's tomb. They were real rocket scientists, and their works are available at
www.Amazon.com. Hope you don't come looking for me later... <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />