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Can you buy an NFA MP5 and swap out the lower onto an HK33?

Discussion in 'NFA Firearms and Accessories' started by TheGewehrGuy, Jul 23, 2011.

  1. TheGewehrGuy

    TheGewehrGuy Well-Known Member

    Will it work on ANY other gun that an MP5?

    Would it be legal?

    Does it matter if its a sear gun or a receiver registered gun?
  2. GoingQuiet

    GoingQuiet Well-Known Member

    If you buy a REGISTERED SEAR gun and the gun is a registered SBR, you can move the sear from gun to gun legally without a problem.

    If you take a sear married gun and move it to another gun you created an unregistered SBR.

    Get it?
  3. TheGewehrGuy

    TheGewehrGuy Well-Known Member

    No not really.

    Lets say I'm not planning on taking an MP5 sear or lower or whatever, and putting onto another MP5, and lets say its going onto a 16"+ rifle (HK33 or G3 or whatever), then we aren't talking SBR, we are talking purely full-auto...

    I think you just confused me even more......
  4. GoingQuiet

    GoingQuiet Well-Known Member

    The issue here is registered sear vs registered receiver.

    You can't move an HK reciever but you can move an HK sear.

    Many guns are SBR'd with a sear, since machineguns have no barrel limitations. When you move the sear to a new gun, you create an unregistered SBR.

    You are looking at the legality of moving a registered sear from Gun A to Gun B.

    Moving the sear from Gun A to Gun B is legal - however in many cases moving the sear creates an illegal Gun A. You have to think about your question in multiple dimensions to accurately answer it.
  5. Aaron Baker

    Aaron Baker Well-Known Member

    I was a bit confused by GoingQuiet's answer until I remembered that the "lower" isn't the gun on an HK. But it IS what causes the gun to function as semi-auto or full-auto.

    Your options, then, on an HK brand firearm is to have a registered sear or a registered upper.

    So if the sear itself is the registered part, then obviously you can move it from gun to gun. But what GoingQuiet is saying is that if you move the sear from a short-barreled gun (which is fine when the sear is in it, because it's a machinegun, and barrel length laws don't apply) to any other gun, then the gun with the short barrel but no sear, suddenly becomes an unregistered SBR.

    But if you have a registered gun (not sear), then it's the upper that is registered, because the upper is the gun on an HK. So imagine that you have a registered MP5 firearm. The upper is registered, but the lower contains the parts that make it full auto. If you remove the lower from the MP5 and put it on an HK33, then you still have a registered MP5 without a lower to enable to fire, and now you also have an unregistered HK33 with the parts to make it full-auto, but not the legal registration.

    Hopefully GoingQuiet can correct my understanding if I'm wrong, but I think that explains the answer to the legal aspect of your question. As for interchangeability between the MP5 and HK33, I honestly just don't know, but I bet the answer is out there on the internet somewhere.

  6. dprice3844444

    dprice3844444 member

    there were some lowers that were registered as smg.atf let some do it,but not others.in most cases the lower/upper bolt carrier were somewhat mated reference timing issues.

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