The U.S. Air Force recently posted solicitation for 150 M4 training rifles coming from Olympic Arms, under the name of Cobolt. This is not at all to be confused with the high end competition AR company similarly named Cobalt. It turns out that the Air Force has been using these trainers for some time now, especially during Air Force basic training. Unlike standard blue trainers made out of plastic, the rifles are essentially a demilitarized version of the M16A2. This is accomplished by turning an actual M16A2 parts kit into a rifle, minus the trigger group and a filled barrel. From what I can gather, either the trigger group has been filled in with some substance, or it just can’t operate if attached to a functioning upper receiver at all. The Trainers can be ordered with either blue or black furniture and are available as a M16A2 or M4 configuration. Olympic Arms made the Trainers, but since the company has gone out of business, this might be an opportunity to provide a similar trainer to the DOD. The need for these don’t seem to be stopping, and they look ridiculously simple to manufacture from existing A2 parts kits.

This is from someone on M14forum.com who used one in the Service–

They look, weigh, and feel just like a real M4, and are made by Olympic Arms, but the barrel has no chamber and the trigger assembly is a mock up. They were made to teach how to field strip an M4, and practicing other things, where a real weapon might not be appropriate or safe. Even up close, you’d never know it wasn’t real except for the “Cobalt Trainer” marking on the left side. In fact, many of the parts appear to be actual parts.

From an Air Force basic training video-

One would ask why bother with a half-way working Trainer when dummy “Rubber Duck” Trainers are cheaper and more plentiful. Or why not just issue a working rifle since those using it are after all members of the Armed Services. Having this sort of Trainer does bring some advantages. For example there really isn’t too much of a worry if a rifle gets lost or stolen. Whenever this happens to an actual weapon in the service, entire bases are shut down and every vehicle existing is searched. This happened at least twice while I was on active duty, once at Parris Island, and another time at Camp Lejeune. Having a Cobolt Trainer allows recruits to be acclimatized to an issued weapon system without damaging or severely breaking an actual rifle. Thinking back to my own Boot Camp, the amount of pure savagery our rifles issued to us throughout the 13 weeks was very intense. Being covered in mud, and kicked down stairs (A DI did this down five flights of stairs, to prove a point. What it was, I still don’t know) couldn’t have been beneficial in any way to rifle accuracy on the qualifying range.