I'm trying to find out which diameter the projectile the SIG 556R bore is optimized for .308 or .311? I have heard you can reload with either with minor performance differences. I'm looking to reload with a 123-125gr 30 cal bullet. Anyone have any knowledge of this or experience reloading for this particular rifle? Any specific recommendations? Curious because .308 bullets are more widely available and cheaper than the .311's.