I just looked in Speer #15 in loading notes for 220 Swift.

Speer specifically recommends 1 in 10 inch twist for the 70 gr SMP. Muzzle velocities range to over 3400 fps with slow powders. Speer states that 14 inch twist will stabilize their 55 gr bullets.

In regards to the 22-250, Speer makes the same cautionary statement that :"As a general rule" a 10 inch twist is required to stabilize the 70 gr SMP.

I can make no claims one way or the other from personal experience. I have not shot that bullet.

People who choose to brew up their own storms bitch loudest about the rain.