Maybe someone can answer this. My 1980,336 (30-30) 20in. barrel has MC rifling with a 1-10 ROT and my 2007 XLR (30-30) with 24in barrel has Ballard rifling with 1-12 ROT. I understand that in both rifles the bullet makes 2 revolutions before exiting the barrel. I guess my question is, why is there a different ROT and type of rifling?? Is the slower ROT (1-12) in a longer barrel with Ballard rifling stabilize the bullet better in the 30-30 ?? Man, I wish I was smart !!!