I would not wait to see if there is an "high grade" XM177 associated with Colt. I would also not rely on the Colt name. Most parts these days are manufactured by several companies that also are contracted to those who are producing military M16s, M4s, and M4A1s. If you are considering buying an XM177 reproduction, Troy has very nice XM177E2 and GAU-5/A/A clones that have been very well received from those who own them and have tested them. Colt is not into the reproduction game as evidenced by them farming out the M16A1 Reissue to US Ordnance. It was originally farmed out to US Armament, but they had to have the project re-routed since they could not devote the time and resources to the program. It is highly unlikely that the general public will know exactly what parts are used for these rifles. Only those who buy them will be able to see first hand what is there. Colt is not the only game in town and has not been for many years now. Troy Industries has done their homework on the line of reproductions they are putting out. They have paid attention to detail. They are also very reasonably priced, unlike Colt. Take a look at the Troy carbines and rifles.
https://myservicerifle.com/troy-xm177e2/
They do not have a M16A1 reproduction at this time. Here are two other models that they will be introducing.
http://www.thefirearmblog.com/blog/2...sfod-d-ar-15s/