Correction:

In my 12-14-11 post to this thread I said I had fired the 70 grainers from 9 and 10 twists and got mediocre accuracy but no yaw. I have been thinking how that doesn't sound right. I dug out the targets and find that I must have been confusing another test with this-- I DID get yaw, at 25 yards, in 9 and 10 twist barrels with the Barnes 70 grain bullet.