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AR15 to M16 Vietnam Era Conversion

Discussion in 'Black Rifle Forum' started by Flipaldo, Feb 19, 2011.

  1. Flipaldo


    May 12, 2010
    I am in the process of doing a full Vietnam era conversion on my AR15. So far I have the non-adjustable stock and all the pieces needed to install it as well as the triangle handgaurds. Are there any other difference look wise? TIA.
  2. surf


    Jul 7, 2010
    The biggest cosmetic cues are the handguards and stock / assembly which you have, but you will also need

    - A1 / A2 style upper receiver, A1 is best.
    - Appropriate rifle length barrel and profile
    - 3 prong Flash hider

    This will give a good replica look, but true aficionado's will pick out details. You might want to check the retro forums at

  3. Nakanokalronin

    Nakanokalronin JMB & MTK

    May 13, 2008
    I bought a modern AR lower, complete original Colt upper with 3 prong flash hider and chrome lined 20" pencil barrel, original stock set and original Colt 20rd mag. Eventually I want to get a remake of the original lower as well to complete it.

    Only thing not original is the receiver and its internals.

    The receiver details are important as well.Correct pins, trigger, upper with all the correct parts. I was lucky enough that someone was selling an all original complete upper but you could always piece one together. You can get a correct lower receiver here:
    Last edited: Feb 19, 2011
  4. Flipaldo


    May 12, 2010
    I am under the impression that M16s from the Vietnam era didn't have a forward assist. Is this true?
    Last edited: Feb 19, 2011
  5. jrs93accord


    Jul 10, 2005
    Pensacola, FL
    The later models did along with a birdcage type flash suppressor. The receivers also had, what we call fencing, on the right side of the lower receiver. The earlier models had the three-prong flash suppressor, no fencing on the receiver, and no foward assist/bolt assist. You will also need to make sure you get an A1 style pistol grip. As for the buttstock, make sure you have the A1 buttstock. There is a difference between it and the A2 buttstock (longer).
  6. lawman800

    lawman800 Juris Glocktor

    I have an original SP1 upper with original BCG (shaved to make it semi-auto) and the A1 pistol grip and stock. The original type lower has no guards around the magazine release.

    The upper I have was modified to fit the stupid 1997 laws in CA by removing the bayonet lug and the 3-prong flash hider was removed and fitted with a pinned 9 port muzzle brake. Yeah, that made it a lot less dangerous.

    In any event, it has the shovel foot forward assist, not the round button type found on the modern AR's.
  7. Mongosafari

    Mongosafari El diablo verde

    Not sure how far you got with the upper assy yet; please take a quick look here:

    I won't bump it to the top again. Make an offer. PM for my email and we can talk.
  8. mac66

    mac66 Huge Member Millennium Member

    Oct 28, 1999
    Blue Planet
    The Viet Nam war era lasted a long time. We had advisers in VN as early as 1962/63 with prototype ARs. The war itself ran from 1965-75 during which the AR/M16 was constantly updated and upgraded.

    Forward assists and chrome lined bores came about because early ammo used the wrong type of powder and rifles were not issued with cleaning kits. They tended to jam up.

    I have an SP1 upper that I returned to it's original configuration by adding the triangle hand guards and three prong FH. I added an A1 stock and pistol grip to my lower. The lower is not correct in terms of pins and raised fence around the mag release but it still has the feel of an early rifle.

    The lower rifle is the SP1 in original configuration. Note the lack of a forward assist.

    The top rifle's upper (forget about the lower) is the next phase. It has A1 sights and a teardrop forward assist. Either triangle hand guards/three prong FH (early) or round handguards and bird cage FH (later) are appropriate for this version. Round hand guards eventually replaced the triangle ones however.

    The middle rifle has the A2 rear sight and a round forward assist.


    If you really want to get into the retro look this website has all the specs
    Last edited: Feb 20, 2011
  9. RMTactical

    RMTactical CLM

    Oct 7, 2000
    Behind an AR-15
    You can still go retro without the 3-prong flash hided. I prefer the look of the A1 personally.
  10. Flipaldo


    May 12, 2010
    Thanks for the info guys. I have all the pieces I need now I just need to know how to remove the circular cap and replace it with the triangular cap so I can add the triangle handgaurds. Can anyone point me in the right direction? TIA.
  11. NeverMore1701

    NeverMore1701 Fear no Evil Platinum Member

    Jun 25, 2004
    Amarillo, Tx
    Gotta take off the FSB.