Originally Posted by Rastoff

I used to believe the same thing, but have learned more. Yes, the powder is done burning at about 18"-22", but that doesn't mean the pressure just disappears. It might not be building, but it's still pushing. The extra 4" will give you a higher velocity without increasing the chamber pressure. This is a good thing when looking for maximum accuracy at longer distances. Out to 200 yards it's only a marginal difference. However, when you get out to 300-500 yards it makes a dramatic difference.