Others and myself wondered the same thing, so I called and spoke to the ATF. I communicated with an extremely knowledgeable specialist at the NFA branch of the BATF and explained that I purchased a transferable full-auto Colt M4 Commando Enhanced with 4 position selector built 1998. I also explained how the general consensus from NFA dealers & collectors is to unanimously condemn this firearm as a mistake, how there's no way this could be transferable, and how this gun is a phone call away from the inevitable swat team confiscation.
The agent was already familiar and well informed of the situation with Colt's modernized machine guns that exist as transferables. He gave me 39 minutes of his time by phone and confirmed much if not all of what I had already been led to believe by people in the know (private collectors with means, AKA the Syndicate). The agent assured me that I needn't worry about this gun being reclassified as post-sample or being confiscated since the serials were registered prior to May 1986. He went on to say that Colt did indeed enhance and remark some of their transferables and how never to take apart the 4-pos because of the complexity (this agent was very much a gun guy). He said that the ATF isn't out there to take our guns away and that the blogs (implying forums) out there are almost always 100% WRONG in their assumptions.
I had also emailed him (and another ATF specialist) the original high resolution pictures that the seller/dealer provided me with and a link to
this thread. I was instructed to include printed photographs along with a memo for the examiner and to instruct the examiner to contact this specialist if there are any concerns.
The original agent that was aware of these modernized Colt transferables was out of office at the time that my file was being reviewed and the examiner assigned was mighty thorough with her investigation, just as I had requested in my included Attention Examiner letter. I have email confirmation from the examiner that the high resolution printed pictures & burned disc pertaining to this very Colt M4 Commando Enhanced, manufactured in 1998, were received to assist in the investigation, "We see an attached letter with a CD of photos attached. Also, noticed the folders have those same photos enclosed." So now, in addition to the special agent that assured me of this Colt M4 Commando Enhanced's legitimacy as a transferable and guided me through the completion of it's form 4, I also have email records with the examiner at the ATF stating that they verified the records with Colt directly, "I have reached out to Colt and am just awaiting a response from them on the proper model designation to ensure we have that 100%. Often they designate “M4” as the model and the following content just being additional variant info." After a 360 day wait, the approved form 4 indeed matches this Colt transferable machine gun exactly/perfectly/correctly, and I have absolute confidence & confirmation that this transfer did not simply slip through the system.
I realize that there will always be some non-owner skeptics that will never admit that a Colt transferable rarer than a standard M16A2 could legally exist and will stubbornly ignore all support/confirmations/blessings that the ATF provides to the contrary. This is the same illogical and yet familiar denial that some non-owners have for machine guns in general, by condemning them as overpriced toys that aren't worth more than their parts.