Alright, so I m beginning the upgrade process on my aac21 m700 (kjw). I am going to rhop the barrel soon and I am stuck on two things considering barrels. One, I will be running 550 fps via co2 conversion and am wondering, which barrel dia would be more effective> a 6.03mm or 6.05mm? I am looking for the best consistancy for the dia and most accurate long range rather than close (Hence sniper). Second part, I will be lapping whatever barrel I get. I feel I can make a crappy 6.03 steel barrel perform better than a prommy 6.03 etc. But I am having issues finding a 6.03 or 6.05 steel barrel for the kjw (I am wanting the 640mm or 650mm length). Anyone help me out? My plan as of now is I will be buying a cheap 6.05 brass barrel from evike for 28 bucks, and lap it. But if a 6.03 is better overall then I will keep up with my search.