Second to my 450b, my next favorite caliber AR is my 6.5g. Midway has a complete upper for sale for a good price. While the one I own is a 24 inch tack driver, the 20 inch one that Midway has is a good compromise for you carbine inclined shooters. Mine wears an AR Stoner barrel that was very well executed back when I got it in 2010. Food for thought if you were considering this caliber. With 123gr Amax bullets, mine is a single, slightly larger than caliber hole for 5 shots at 100 yds. Definitely easy to work up accurate recipes across many different powders and an excellent confidence booster and a good choice for CX2 and lighter game. Reliable mag feeding is not an issue in the 6.5g.
Hoot