Colt M16A1 Rifle Cutaway

Lots more pictures of this over at Gears Of Guns.  They had it listed as an AR-15, but I made the executive decision that it was an M16A1 based on its distinguishing characteristics.

Almost brings a tear to my eye to see that someone did this to an auto lower, even though it would apparently still work fine if a regular non-cutaway upper attached.  Can’t really operate in extreme operations with your lower parts being that exposed though.

I love looking cutaway firearms.  It really gives more of an appreciation for all the work that went into creating them.



20 responses to “Colt M16A1 Rifle Cutaway”

  1. I agree as well. While the picture is great. It’s a sad day for that auto lower to be altered beyond practical usability.

  2. I thought the title said “Giveaway” at first. Definitely caught my eye, but a great post regardless.

    1. ENDO-Mike Avatar

      I wish I could swing this sort of giveaway!

  3. Mike, do you see any significance to the XM on the second pic? The original designation of the Army version was XM16E1.

    1. ENDO-Mike Avatar

      Ah gotcha.. so it was pre M16A1 according to Wikipedia because they made a couple design changes to this one. “On February 28, 1967, the XM16E1 was standardized as the M16A1.”. Thanks!

      1. It’s interesting though that it has the “birdcage” flash hider on it instead of the earlier 3-prong style that M-16’s started out with. I suppose that could have been replaced later on.

        I’m good with cutaway drawings though; they do a lot more to show me the internal workings of a firearm than this does.

      2. I think the original lacked the forward-assist. That was something the Army wanted. At least according to the Wikipedia article. Though I don’t know if it was added to the M16 or the M16A1.

        On a slightly related note, that article says it’s direct impingement, but I read something a while back that said that’s not totally accurate. I might have it saved somewhere. It said that in a direct impingement system, the gasses would impact the bolt face directly, which of course isn’t the case.

        1. The XM16E1 had the forward assist – it came out 3 years before the M16A1, and was marked as an AR-15, with XM16E1 written below where it said “Property of US Govt” (at least in the pictures I’ve seen of them). I guess the later models did have the birdcage flash hider. The XM also had the newer charging handle design, which can be seen on this model.

          in a direct impingement system, the gasses would impact the bolt face directly

          I don’t see how that would work, since the bolt face would be inside the chamber, how would you redirect gas into it? I’m pretty sure that direct impingement just means it doesn’t have an enclosed gas piston assembly.

      3. was pre M16A1 according to Wikipedia

        You know what though, in looking more closely at the pictures on the site, it looks like this one has the newer buffer design; the XM16E1 had the older design of the M16. Also, upon closer inspection, this looks like it has a “full fence” lower receiver; the XM16E1 has the partial fence type. It does look to me like it must be an M16A1.

  4. wantsanM1A Avatar

    He’s right you really cant do a whole lot with your lower parts exposed. It’s always ended badly for me.

  5. Can’t you just transfer the Drop-In Auto Sear to another lower and, with the right parts kit (M16), have another auto lower?

  6. JScottNH Avatar

    There’s millions of full auto M16s out there…. No use crying over cutting one up… What’s tear worthy is that we, as citizens, cannot manufacture new ones, or own them unless they were registered way back in the good old days…

  7. That is so awesome! Before I made the plunge and started my build I had watches so many hours of videos and reviews that by the time I had all the parts in front of me I was able to build it without instructions. This is an awesome demonstration tool. The bolts cam pin still doesn’t make a whole lot of sense to me. Theres that “almost rectangular” notch in the upper receiver that from what I can tell cycles the cam when the bolt returns to battery, but I’m not 100% sure its designed to do that. It could just be space for the cam to rest when cycling. I dunno. She runs great regardless.

  8. At first I thought these were pictures of a new “Danyo Defense” lightweight rifle endorsed by the LAV. I was mistaken.

  9. The info my reader sent to me said that the rifle was “FROM THE ESTATE OF THE ENGINEER WHO BUILT THE FULL AUTO AR15/M16” Being that this was a cutaway prototype it is marked with the XM and not branded as a full M16 (or XM16A1 or XM16E1) but a full automatic AR(malite) 15 rifle.

    if you have any more questions on this weapon please feel free to check out and shoot me an email at [email protected]

    and ENDO kudos on the reblog. always much obliged.

  10. AR15 is still correct. M16/XM16E1 etc are just military designations for the same weapon. In the US, AR15 has come to mean ‘semi-auto civilian equivalent of an M16’. Not actually true. All M16s are AR15s – not all AR15s are M16s.

  11. TheMirage Avatar

    When I took my AR armorer’s course I got to handle one of these. Colt still makes these for instruction. Really helpful in seeing all the parts in action.

  12. That is a cutaway gun used to show how the firearm would function and fire and its for sale from