Twist is over rated, I had a custom Savage 22-250 with a 1 in 17 twist barrel, made it up to shoot the light 40 gr bullets fast. It would stabalize a 55 gr bullet out to 100 yards. The stability calculators use a formula that has the spin rate of the bullet slowing down in the same ratio as the velocity does, this does not happen in real life, the velocity slows down a far larger percentage than the spin rate does, so when you look at where the bullet should go unstable it really doesn't happen there, it happens a lot further down range. If the crown is perfect so it doesn't blow the bullet over leaving the muzzel you will be surprised how heavy (long) a bullet you can shoot and still be stable. Larry