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9mm Conversion AR uppers

drecon Feb 4, 2017

  1. drecon

    drecon JDBA4L JDBA Official Member

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    Curious if any of you are familiar with these setups?

    I am specifically interested in conversion uppers for standard ar-15 lowers. I am not interested in dedicated 9mm lowers. I have a registered SBR already that I would like to build/buy a 7.5" (give or take) 9mm upper for.

    I am trying to figure out what mag block is the best? I keep reading Hahn Precision, but my understanding is they have to be "fitted" each time instead of drop in. I want to be able to remove the upper, take out the block and switch to another caliber upper setup without tools at the range.

    This brings me to my other question as from what I am reading it seems you need to change out the buffer to a heavier & longer buffer to function properly for 9mm. What does this buffer do for shooting 5.56/300blk/etc? will the heavier longer 9mm buffers still allow it run properly? Or do you have to change the buffer out each time as well?

    My goal is a setup where the only change out is the upper and mag blocks between calibers.

    I appreciate your input!
     
  2. seandavid55

    seandavid55 JDBA4L JDBA Official Member Brigade Member

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    Well I use a Hahn dedicated block. I read a lot of horror stories about people fighting feeding issues and I wanted to avoid that. Everything I read said go with the Hahn and I have had no problems.
    You don't have to have a longer buffer. It just shortens the stroke of the bolt. 9mm is a lot shorter. They do have just spacers.
    As far as weight, I use a suppressor on my 9mm and 300blk sbrs. I also have heavy buffers in both of them. Took some tuning in the 300blk but the 9mm was just good to go. Can't help you as far as 5.56.

    Good luck. My 9mm AR is just about the most fun gun I have.
     
  3. drecon

    drecon JDBA4L JDBA Official Member

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    Thanks for the reply! If you don't mind a few more questions?

    What exactly do you mean by "dedicated block" is this in regards to it having to be pinned/screwed/locked into place? One of the points I don't really understand. Does Hahn make a non-dedicated block?

    Are you running colt/uzi mags, or glock mags? I'm leaning towards the colt mag setups.

    Have you ever slapped a 5.56 upper on your heavy buffer lower to see if it would work? Im a bit worried that what I want to do can't be done, but my research has found scattered reports of specfic builds working like I am wanting. I just don't know if that is by pure chance or not. Unfortunately most of those specific builds are from a few years ago on random forums, or are comprised of components that are no longer available, or that I am not interested in using.

    I'm trying to plan a build but damn some of this is confusing! I am also not heavy into the AR's so I'm struggling a bit. I'd rather build so I can pick and choose how it ends up looking, but some complete uppers can be found super cheap!
     
  4. seandavid55

    seandavid55 JDBA4L JDBA Official Member Brigade Member

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    The dedicated hahn is installed from the top of the lower. The one your after pops right into the mag well just like a magazine. Then it will have a tension device to secure it. It's not an adjustment, it just tightens it into the mag well. Hahn does make what your looking for. It's right on their website. But I think it's only compatible with certain uppers.
    I haven't put a 5.56 upper on my heavy buffered lower. So I can't help you there. I do use the colt magazines.

    There a lot of components out there. Guns can be annoying when they are not functioning properly. If you make sure everything is compatible and from quality manufacturers then you'll be ok.
     
  5. drecon

    drecon JDBA4L JDBA Official Member

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    Thanks again for all the info, this one is a slippery slope it seems!
     
  6. drecon

    drecon JDBA4L JDBA Official Member

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    Well I just wanted update this thread in case anyone was curious. I've MOSTLY completed my build. Still want a handstop for the bottom rail, forward of the grip. Can't make up my mind on which I want. Still need to upgrade to the KNS anti-roll hammer/trigger pins as I've read they help keep you lower from getting abused. Since this is my registered SBR lower I want to keep it in good shape. Also going to switch out the muzzle device eventually but again I haven't decided on one. Using a temporary red dot sight for the moment, I will be going with a Vortex Venom red dot in the future. Last but not least I haven't decided on if I am going to run a set of back up flip up sights or not.

    Anyway here she is, I'm super happy with how it turned out!!

    Stows away nicely in a laptop bag, and disappears completely in an okay "kitchen sink" backpack!

    The build sheet:

    New Frontier Armory Side Charging Billet Upper Receiver
    SLR Rifleworks Solo Intreped 5.25” Handguard
    Macon Armory 9mm BCG/Mag Block/5” Barrel (1/2x28)
    Magpul RVG Forward Grip
    Custom Thread Protector/Flash Can (temporary)
    Vortex Strikefire Red Dot (temporary)
    Seekins Precision SP223 Billet Lower Receiver (Registered SBR)
    MVB Industries ARC 9mm Stock
    Magpul MIAD Gen 1 Grip
    G&R Tactical LPK
    32rd Colt SMG Mag’s
     

    Attached Files:

  7. XxGRYMMxX

    XxGRYMMxX The Crayola Kid JDBA Official Member

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    nice bug out gun. I dig that stock unit too.
     
    begreen61 likes this.
  8. begreen61

    begreen61 Deadicated JDBA Official Member Brigade Member

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    Thats a Nice.
     
  9. drecon

    drecon JDBA4L JDBA Official Member

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    Thanks guys, I'm just super happy with how it turned out! Love this little guy!

    Last weekend PSA ran a sale on their PSA branded metalform magazines for these. $12.99 a piece, I couldn't resist and bought a few!
     
    seandavid55 likes this.
  10. Brock Samson

    Brock Samson S4supply.com Knife Maker or Craftsman

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    That is a super nice looking SBR. I love that stock, side charger!
     
    Last edited: Aug 19, 2017
  11. zephyr05

    zephyr05 Little member Brigade Member

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    Here's my Colt 6951 SBR. Barrel was cut down my ADCO, suppressor is a SiCo Omega 9K. I do have a heavy buffer in it, 9Q from Heavy Buffers plus a Wolff extra power spring. It slows the bolt down a bit and lessons the felt recoil. It's been 100% reliable.

    [​IMG]
     
    Brock Samson likes this.
  12. sam eib

    sam eib Average Member

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    l
     
  13. sam eib

    sam eib Average Member

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    Looks good, I had an at pistol I was going to sbr but I didn't like the idea of batf having the option of coming to my home checking out my stuff. I built the pistol but sold the upper and put a rifle upper on it. Lots more useful, pistol upper was 7 1/2" and you had to use plugs and muffs it was so loud. It was fun but mot to practical, but mine was 5.56, your 9mm I'm sure isn't near as loud. Have fun with it!
     

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