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Mag block and 9mm mags

Discussion in 'NFA & Class III Discussion' started by bigbang, Jul 22, 2010.

  1. bigbang

    bigbang Sharpshooter

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    I just received my 7-1/2" SBR 9mm upper for my SBR AR lower. I now apparently need a mag block and a 9mm mag. Where is the best place to get these.
    I am going to put my Cobra M2 suppressor on it and use Winchester Super-X 147gr FMJ Encapsulated ammo.
    Does all of this sound ideal? Anything I'm missing?
    Thanks
     
  2. Wall

    Wall Sharpshooter

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    You may end up needing a heavy buffer or heavy spring or both, maybe not (mine doesn't). If you find that your rifle is cycling too fast, change out to a heavy buffer. I run a stroke limiter in mine. It's just a spacer at the back of the buffer spring. It prevents the BCG from cycling past the opening in the lower behind the bolt catch. Without it, the opening is big enough for an FTE casing to fall down in the trigger group underneath the BCG. I't's not necessary, but I like the assurance of nothing going down in the trigger group. Spike's sells them for ~$15. They're really easy to install & remove.

    As for the magwell & mags, you can get them from RRA, Spikes, many places. Cavedweller is/was selling some in the classifeds. I use a Hahn top block with c-products (old style) mags & mine runs awesome. Many don't like the top load hahn block because it doesn't hold the bolt open on the last shot. Most seem to prefer the dedicated bottom block. The only problem is that it takes a tool to remove it. It's not as nice as the top IMO for swapping uppers at the range or in the field. It's just a mtter of prefference really. As far as mags go, it's hit & miss. I use older c-products mags. I'm not sure what they changed, but the newer ones don't work very well. BTW, this is the report of many users, not just me. Some like midified uzi mags, RRA sells mags. FWIW I've never been able to get a poly mag to run reliably in mine. Your best bet is to not go hog wild on mags until you find out which ones run best in your gun. 9mm AR's are all different. Even 2 rifles built the exact same way with the exact same components & ammo will run different & 1 could be more reliable than the other. My advice is to take your time tweaking & working out the bugs before you waste alot of money on mags. Then after you find what runs best for you, don't change anything.

    Good luck, have fun.
     
  3. WhiteyMacD

    WhiteyMacD Sharpshooter

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    I use Hahn bottom loading (non dedicated). 4 full turns of the allen key and its out so it doesnt take THAT long. Benefit, bolt hold open. I run a standard Roggio Arsenal LPK hammer (type of hammer is going to depend on your bcg. My bcg will not work with dedicated 9mm hammers), and a spikes heavy buffer with spacer.
     
  4. Wall

    Wall Sharpshooter

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    unless you're like me & always forget to bring 1 thing or another. In this case, I'd have my entire set of allen wrenches except the size it takes for this swap. That allen wrench would be laying on my bench, from when I installed the dang thing.
    :pms2::pms2::pms2:
     
  5. WhiteyMacD

    WhiteyMacD Sharpshooter

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    What takes me the most time to get it out is trying to figure out which allen key it is in the bottom of the bag because I never put them back in the holder.
     
  6. bigbang

    bigbang Sharpshooter

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    Thanks guy's for the info. Can't wait to shoot this thing!
     
  7. Risky_Rooster

    Risky_Rooster Sharpshooter

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    To add to bigbang's question: Is there any reliability bonus for going with a 9mm receiver vs putting a mag-block into a 5.56 receiver?

    I know you lose the ability to convert to 5.56, but do they run any more reliable because they're purpose built for 9mm? I'm interested in the RRA 9mm receiver, but its not worth it if it doesn't run better/more reliable than dropping a conversion kit w/ mag-block in a regular receiver...
     
  8. WhiteyMacD

    WhiteyMacD Sharpshooter

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    Im no expert, but I dont see how they would have an advantage. The Magwell of the 9mm reciever looks exactly like a 556 magwell with the block in it, except its all one piece of aluminum.
     
  9. Risky_Rooster

    Risky_Rooster Sharpshooter

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    That makes sense. I was just thinking less moving parts, ect. I have a low tolerance for guns that don't go bang every-time (FTF FTE ect). But if ur saying a highly reliable 9mm AR can be had with a drop in, then that's definitely the way I'll go.

    Thanks Whitey!
     
  10. Stoverarms

    Stoverarms Sharpshooter

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    An option on your mags would be to get UZI mags and notch them for the AR. I use this setup as I already have a ton of UZI mags and I makes it easier to pack one set of mags that work in two guns.
     

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