I have noticed that most fast shooting .224 caliber rifles like a 22-250 or a 220 swift have a twist rate of about 1 in 14 or 1 in 12. Although I have read that if you want to shoot a heavier bullet like a 75 grain, you need a twist rate of 1 in 8 or faster. Why not use a fast twist rate for the lighter bullets also, or is that a problem? And if not why dont factories originally have the barrel with a twist rate of 1 in 8?