Try searching Calguns.net and AR15.com for your answer. Be forewarned that this will likely end up a Ford vs Chevy vs Chrysler type question.
That being said, I have both Rock River and CMMG builds...if you live in Kalifornia, you have to be careful that the lower receiver is not on the banned list...
Riflegear in Costa Mesa and Coldwarshooters in Highland are good resources if you want to go look, touch and buy.
BTW I have a Mak-91 for sale (in AZ), not Kalifornia legal.
That being said, I have both Rock River and CMMG builds...if you live in Kalifornia, you have to be careful that the lower receiver is not on the banned list...
Riflegear in Costa Mesa and Coldwarshooters in Highland are good resources if you want to go look, touch and buy.
BTW I have a Mak-91 for sale (in AZ), not Kalifornia legal.