Re: questions about bullet weight vs twist ratio
The length of contact in the barrel affects yaw of the bullet so that can affect the BC and stability. However length and the bullet design has more to do with the need for a certain twist rate . The centre of pressure and mass of a bullet is changed with the change from a flat base to a boat tail or the change from a low calibre ogive to a high calibre ogive etc . In every case the bullet mass is moved about with respect to the centre of gravity along the entire length of the jacket . A typical example is Barnes Varmint grenades .
the short bullets need a twist rate that is way faster than other heavier bullets the same length. Why ? Because the whole ogive is hollow and all the mass is in the base of the bullet moving the centre of pressure way to the rear and increasing the potential for yaw and to tumble or wobble and become unstable .
To understand why one bullet needs one twist and another similar profile bullet needs a different twist you need to understand and compute many variables .