I just got my 300/.221 on a rem 700 with a 16in barrel. The 556 brass is to thick for a true 300 whisper chamber. I put about a 50 rounds through my 700 556 brass cut and necked up with some 178Amax and 220 SMKs just seeing what the 1-8 barrel liked. Both shot well I am still waiting on the Major for my Cyclone to really work on some sub sonic loads. they are a blast its got me thinking about a AR upper.
Dustin
Dustin