canadian shooter, since you put it that way I'd keep the rifle and configure it to suit your taste. Like GT mentions, it has a govmnt profile A2 barrel with 1/7 twist. Somewhat of a rare bird in the civie gun market for some strange reason. If you want a flattop than pick up an A3 or A4 upper without M4 feedramps if you plan on using that barrel. I believe that your Colt has the large pivot pin, no biggie, you just need the bushing to use any milspec upper or Daniel Defense does make a large hole flattop if it really matters to you. Believe trigger pins are mil spec, so install whatever you like.
FYI: A3 uppers are flattops, A4's are flattops with a numbering system in the cross slots. M4 feedramps are extended feed ramps, you don't want those if you have a regular barrel extension since the tips of the bullet can get hung up between the ramp and extension.
FYI: A3 uppers are flattops, A4's are flattops with a numbering system in the cross slots. M4 feedramps are extended feed ramps, you don't want those if you have a regular barrel extension since the tips of the bullet can get hung up between the ramp and extension.
