Hueco, yes, increasing the velocity will also increase spinning rate linearly, but in a given caliber you don't have much room to get the 20% increase in velocity needed to compensate from 1 in 10" to 1 in 12", that's why you are restricted from the beginning to a certain range of optimum bullet lenghts (and weight). As Southla1 said, sometimes you get different results in the real world (and nobody knows why...). Load development is a different thing, and is basically selecting components (one bullet, different powders/primers)and trying different combinations until you achieve the results in velocity, consistency, pressure, and accuracy that you desire. Past this you try different seatings depths (and MANY other thigs) to fine tune the load. Look in www.snipercountry.com
, there are a couple articles on this.