I have a DPMS AR chambered in 5.56 x 45 mm. Can I shoot any .223 I want out of it? I've only shot 55 gr so far. Can I run 70-80 out of it with no trouble? Are the heavier bullets longer? Will they jam into the rifling? Are the heavier bullets too long to fit in a magazine? I only have a 1/9 twist so I don't know that my gun could handle the heavier bullets anyway.