10" Complete Upper Compatible with Colt mags

[RangerTrace]

So, I'd like to buy a complete  upper for my AR9 that currently has a 5.5" barrel and Octane 9 can.  I know a ton of you have already done the homework for this kind of project.  What is the best route to get a reliable/accurate upper that won't break the bank....

[ericskennard]

I love the  Rock  River 10 inch upper. If you are trying to build on a tight budget, look at www.ljsarparts.com