I don't have an A-bolt but do have 2 BARs in 338WM. One has the Boss system and the other doesn't. The Boss equipped rifle is a little bit longer. The biggest difference I and my hunting buddy noticed was the extra noise with the Boss. My buddy doesn't want to hunt near me when I have the rifle with the Boss and I also noticed it was louder. These days, I use the non-Boss BAR and it works just fine.