Arms Unlimited has a small number of European specification carbines available for purchase.

https://armsunlimited.com/colt-carbine-223-semi-auto-rifle-european-model/

This model is unique in that it has a serial numbered lower receiver, upper receiver and (I believe) bolt carrier group. It is actually .223 because the customer country can’t own 5.56mm. Comes with 1x 10-round magazine.

The following discussion involves a part that isn’t Colt. However, it is a unique and not commonly known piece of M16/M4 history.

When I began my Army career in 1988, I was a traditional weekend soldier in the National Guard. The hot topic at the time was DSCA…Defense Support to Civilian Authorities.

DSCA was a domestic plan for the National Guard to provide soldiers to Law Enforcement for both natural disaster/non-kinetic environments and potential kinetic environments such as riots.

In a DSCA scenario, Governors and law enforcement officials were concerned with the potential for troops to panic in a violent encounter and rotate their selectors to ‘Auto’ and firing on civilians.

A concept to mitigate the risk of unintended casualties from automatic rifle fire was this selector block that prevented the selector from rotating from ‘Semi’ to ‘Auto’.

In this video, I give you a look at the part, talk about its installation and give you a look at it installed.

The firearm used in the video is the Colt CRM16A1.