Hello all,

I am looking to build a new ar-15. So far I have a lower from PSA. I am running into a problem trying to decide what spin ratio I want for my upper. After looking through PSA's uppers, I noticed they only have 1:7 twist ratios. My question is... if I plan on shooting 55g bullets here in Colorado... will that twist ratio be too much? Also, what kind of range are 55g bullets accurate to?