Most 30-06's run 1 in 10 twist barrels. Most Garands are 1 in 10 and prefer 150-155gr bullets. I have a Garand with a NM barrel which is 1 in 9 and will shoot 168gr bullets well. But all of this goes out the window as soon as newer solid metal bullets are substituted.
It not so much the weight of the bullet, it is the length that governs the twist requirements. The new all copper bullets out there are longer than their same weight Conventional Bullets, as a result they are requiring faster twist rates than previously considered normal.
AR's now have 1 in 7 twist barrels available made to shoot 80-90gr+ .22cal bullets for long range match use, however if you try to run small bullets like 45-50 gr varmint bullets in these fast twist barrels they blow up from centrifugal force as soon as they clear the muzzle. Poof.
On the other end of the spectrum,,,
My Marlin .44 Magnum Rifle and Carbine both have 1 in 38 twist barrels and will not stabilize any bullets longer than about 265 gr. The loose bores at .431 doesn't help either. They are both made to shoot short fat bullets, and they don't even do that particularly well. In fact both of these guns have abismal accuracy which is why they are both going to be rebarreled with 1 in 20" twist barrels. Then they will both shoot up to 330 gr bullets accurately. Right now 3" at 50 yards is a good group. 1.5-2" at 100 yds is more what I'm looking for. With the 1 in 20 barrels I should be right in there. I want to be able to run 250 gr bullets at 2000 fps and 300 gr bullets at 1800. This is 45-70 power in a 36" long carbine,, Which will also have a decelerator pad and maybe even one of those Mercury doodads in the stock for good measure. Good companion for a .44 Bisley Revolver and able to shoot the same ammo.
This is a fascinating subject and I don't think you can have too much info, as it is the very essence of the rifle. Why and how they determine the twist rate for a given bullet is not clear. I wonder if it is done by trial and error or if they can predict based on length versus diameter?
Randy