Colt AR15 A2

Discussion in 'AR-15 Discussion' started by Dusty123, Jan 16, 2012.

  1. Dusty123

    Dusty123 New Member

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    First off Im a newbe. I built a RRA lower with DD LPK. Its complete so I barrowed my friends Colt to try out his upper. Well I found a few things different about it. I was hopeing to learn alittle more about it. It says it a AR15 A2 HBAR sporter. The upper says C M P 1.9. The front Take down is 5/16" not 1/4" so I cant use it. The hammer spring legs are on the floor of the lower not on the trigger pin, is that right? The Disconnector is shorter than mine and the Discon. spring is located closer to the trigger pin. It came with a aluminum firing pin wich he had changed to titanium. Why would you use aluminum? Last the stock is a 4 pos. thats all metal and its loose. I know that isnt right but did it come with that? Like I said Im new so forgive me if these are stupid questions. Thanks
     
  2. Gatoragn

    Gatoragn Active Member

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    The pivot and takedown pins are larger on colt ARs, that much I do know.

    So you cannot mix & match colt lowers & uppers with other brands of lowers & uppers.

    But your RRA lower should work fine with Daniel Defense, LMT, DPMS, BCM, etc...
     

  3. Quentin

    Quentin New Member

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    Kinda hard to understand what you're asking. I guess you've given up on using your friend's Colt upper on your RRA lower, but are you still asking questions about the Colt? Or your RRA lower? It does sound like the hammer spring is wrong, it should be on the trigger pin, in fact the spring holds in that pin. You sure that's an aluminum firing pin or steel?
     
  4. Dusty123

    Dusty123 New Member

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    Sorry. I was asking about the colt. Thats what I thought about the spring. And yes the pin was aluminum and smashed on the end. It seems like someone butchered the Colt. He allways has problems with it.
     
  5. Quentin

    Quentin New Member

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    A shame about the Colt, hopefully a little effort will get it back in shape. There are pin adapters to work with oversize uppers and lowers but they're not cheap so probably not worth it. Would make more sense to keep trying to find a standard upper to test your lower. Not a big deal if you can't, you can test out a lower without actually firing it.
     
  6. Dusty123

    Dusty123 New Member

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    Ok thanks. I will fix up the Colt before I return it to him. Why would the disconnect be shorter in length? Is it just a different design?
     
  7. Quentin

    Quentin New Member

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    Not sure about the Colt disco but if it works properly I wouldn't mess with it. You can test the trigger function with no upper on but be sure to catch the hammer with your thumb, don't let it slam against the bolt release. Cock hammer, pull trigger (keep it pulled back), catch hammer with thumb, recock and see if the disco catches it, then release the trigger and see if the trigger catches the hammer back while the disco lets go. Do this repeatedly until you're sure the trigger function is ok. You can test this against your RRA for proper function.