How does the 11-12 twist get more velocity?
Recently a writer said he tried a 11 twist barrel and saw minimal increase in velocity compared to a 10 twist. The velocity in most cases does not just magically appear. The 11 and 12 twist barrels with high performance rifling specs lower the peak pressure in the chamber and barrel, that allows handloaders to add more powder to get back up to max peak pressure levels and that increases velocity, sometimes as much as 200fps over factory ammo. If all barrels had better specs factories could load higher performance ammo but due to the 9.5 twist barrels floating around they would be liable if the stronger ammo destroyed one of those rifles.
