Colt does still produce 9mm rifles and components - but only in "pre-ban" config for LEO rifles. While the only Colt-produced 9mm complete rifles are LEO-only, you can find spare parts, and they could be modified for a post-ban build. Expect to pay lots.
Least-cost for a Colt style system would be RRA, I think. Usual parts to change for a Colt system are the bolt catch (only needed if you're using Colt factory mags, which can actuate the bolt hold-open), and the hammer, if you're using a closed-top Colt semi-auto style bolt/carrier. You can still use the 9mm hammer with a .223 upper, but a stock semi .223 hammer won't work with a closed-top semi 9mm bolt.
My Olympic has been extremely reliable. I've broken 2 extractors in 5k to 6k rounds. One broke on its own around 3k, the other blew off when I had an OOB (using a brass catcher, and it bounced an empty back in the ejection port - so not really the rifle's fault).