No one can take this overall subject and condense it to a single category.

It not just "one thing"; jumping or jamming, long vs short bullet, heavy vs light, plus no one mentioned long vs short freebore, or slow vs long burning powder, and I can't recall if long vs short barrel length, or the number of groves in the barrel, etc.....

It's all of the above: All things being equal, you can't have a long bullet without weight--now before someone jumps off their horse, I did say all things being equal--each type of bullet is different but in the formula(s) for design weight cannot be dismissed: http://www.riflebarrels.com/articles...et_weights.htm

Therefore the velocity, bullet design, seating depth, barrel length, powder burn rate, freebore, neck tension, and case design (is there room for the correct powder/bullet combo) etc.... All have to be taken as a whole to predict how a particular bullet will act, in a particular twist rate....

JBM has a great calculator, it enhances ones ability to calculate the outcome in principle and in practice

http://www.riflebarrels.com/articles...et_weights.htm