The bullet may rotate more than that, here's why. When the bullet arrives at the target, regardless of velocity at the point of impact, the rotational velocity remains, for the sake of argument, unchanged because there are few forces working to slow it down. The bullet penetrates the skin and begins to expand in the tissue, and while this happens its velocity is dramatically reduced from super-sonic to sub-sonic to stopped within a very short distance, lets call it 24". While the bullet is supersonic, for about half of this distance, or as you point out the width of a broadside deer, the rotational velocity has not been effected to any large degree because it is not in contact with soft tisse due to the super-sonic shockwave around it. Let's assume the shot was a long one and the bullet arrives on target at 2200 fps. By the time that 12" has been penetrated, the velocity has dropped below 1100 fps, yet until now, the rotational velocity is still in the neighborhood of 4260 revolutions per second as it was when it left the muzzle. The average velocity through the deer is perhaps 1500 fps, so it takes the bullet .00067 seconds to pass through the deer and that means the bullet can rotate 2.8 times.