Tim, I'm not a gun/ammo whiz like some of you guys/patriots but I do know this, as old as I am and as bad as I shake and with a little ra in my hands you don't want me shooting at you with either of my miniG's! The barrel length seems almost negligible. I think my .308 is a little more accurate than the 30.06 based on seat of pants and the SWAG rule. I've never tried to adjust either of my gas plugs but I've never had the reason to mess with them as both rifles have always cycled correctly.
Bill