I was issued both the E1 & E2 versions in the late '70s. As I recall, they were marked AR-15, US Property, Colt Pony, but I seem to remember at least a couple that were stamped XM177 (with no "E-" designation). Never saw the word Commando anywhere on the weapons. All of ours had forward assists. They were all select fire with safe/semi/auto only. The lowers were original to the weapons.
We simply refered to them as CAR-15s. They were considered way cool at the time and issued to Plt Ldrs, Plt Sgts, Squad Ldrs, RTOs, designated point men, etc. Interestingly enough, most of the weapons were war veterans of SE Asia which were left in country at the end of the war. They were later "re-purchased" by the US Govt thru a third party arms dealer who procured them from Communist Vietnam. Most had seen heavy use (lots of war in the region after the departure of the Americans and even after the fall of the South). Strange how the wheel can turn full circle.
Most fired ok, but some had severely shot-out barrels (almost smooth bore) and some had damaged/mis-aligned flash suppressors. The first one I was issued would literally keyhole rounds thru a 25 meter zero target (bullet hitting paper nearly sideways and punching an oblong hole thru the paper). Needless to say, I DX'ed it quickly. Although it would have been lethal out to 25-30 meters, I couldn't reliably hit a damn thing past 50 meters. Not the weapon's fault...just clapped out. As the original flash suppressors occasionaly wore out (mostly from young studs repeatedly unscrewing them for detailed cleaning), they were replaced with standard bird-cages. This made for a lot louder weapon and significant (blinding) flash at night.
They were fun and handy (especially to rig for airborne ops)...a piece of history in your hand...but today's M4A1 is a vast improvement. I would not think that very many ever found their way into PDs or legal Class III registration.
Figure The Odds...