Need help. Trying to decide on an M4. Can anyone tell me more technically about the Colt 6721 & 6920. Specifically are the bores chromed, any other parts chromed. What makes them “LE”.
And yes, the bores, chambers, and inside of the bolt carrier are hard chromed.
They are “LE” because they have features that were banned by the now defunct AWB on 1994 that their “civilian” Match Target rifles don’t have.
Can anyone further explain the Colt LE features. I have been to the colt website and they say nothing about chromed bores etc.
The search function is your friend 
Bayonet lugs, collapseable stocks, flash suppressors are the “banned” features that are no longer banned in most states.
They’re hard chromed.
Have you taken some time to read some of the stuck threads here in the forum? They should go a long way towards answering some of your questions.
Main differences is the 6721 is an HBAR (heavy barrel) with a 1/9 barrel twist.
6920 is M4 profile, and 1/7 twist.
Other than the barrel they are identical.
Id go with the 6920 due to the lighter weight, and the 1/7 barrel twist to stabilize bullets 70 grains and above. Vast majority of 1/9 twist barrels will max out at around 69 grain bullets before they can no longer be stabilized.
and the cool roll mark that reads;
RESTRICTED
MILITARY/GOVERNMENT
LAW ENFORCEMENT/EXPORT
USE ONLY
seriously, look into the sticky threads and follow the link to the “chart”.
I have a 6920 and its a great rifle, put a Daniel Defense Omega rail on. I normally use 75 grain ammo and its really accurate, highly recommend! Good luck