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Thread: 9mm AR Build - Am I missing anything?

  1. #1
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    9mm AR Build - Am I missing anything?

    I have a 5.56 pistol build that went well and I want to add the capability to run a 9mm upper with it. It will be a bit cheaper to run, quieter and shoot be fun (recreational build).

    I am pretty confident with 5.56 builds, but just want to make sure I am not missing something obvious. Please let me know if you see anything missing or a problem with my build.

    Lower:
    Complete pistol lower with a PSA polished and plated mil spec FCG, KAK Shockwave Blade and RE
    Standard (BCM) carbine action spring
    Foxtrot Mike 6.5 oz 9mm (extended) buffer
    Mean Endomag/Pmag Gen2 conversion

    Upper:
    11" KAK 9mm barrel w/flash can
    "Sport" upper rec.
    Spinta 9mm bolt (16 oz)
    10" ALG rail
    Sights

    The only things I am waiting on are the endomag conversion and buffer.

    Thoughts?

    Thank You

    Andy
    Last edited by AndyLate; 09-23-19 at 18:48.

  2. #2
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    Just some advice.

    9mm builds are not as easy as 5.56.

    They can have feed problems (and sometimes ejection problems).

    Conversions/adapters/BS only make those issues worse.

    Magazine related failures are the #1 cause of issues in any platform.

    A dedicated Glock mag lower such as the FM-9 is a worthy purchase and the LRBHO is nicely executed.

    You're on the right track with the extended buffer, but that one is a single solid part.

    The FM-45 buffer is even heavier at 8 oz and has a couple moveable tungsten weights to help with bounce.

    Verify the barrel has a proper feed ramp / cone. If not, 147gr flat points and defensive ammo may not feed.

    Everything else looks fine.
    Black River Tactical
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 11.5" CQB, 9" PDW
    BRT OPTIMUM-S Barrel - 11.5" CQB Suppressor Gas Drive
    BRT OPTIMUM-S Barrel - 11.5" SB Suppressor, 11.5" SBT 25 Deg Tapered Shoulder Suppressor
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT EZTUNE Gas Tubes - CAR and MID
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  3. #3
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    everything else looks good, but I would go at least 7.5 oz buffer and possibly 10 oz buffer. Also upgrade to a .308 buffer spring as well...

  4. #4
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    I'll be following this. Picked up my first 9mm lower this morning.
    You know what I like best about most people?

    Their dogs.

  5. #5
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    It may be my bolt or lower, but Clint was spot on about headaches with the magazine adapter (endomag).

    You have to "break in" the magazine shell, then the endomag insert. It seems kind of hokey, and mine is still pretty tight after following their written and video instructions. I only converted a single magazine at this time.

    I shot about 150 rounds today with the single 30 round converted pmag; sometimes it would run through a magazine perfectly, other times it seemed like the endomag was dragging the bolt enough that it would either not chamber or not quite close into battery and the round would not fire. I was using factory second speer ammo, but I don't think that was causing my issues. I will clean and lube tonight and try it again tomorrow and bring other ammo too.

    Reliability frustration aside, I like the gun. I was shooting golf ball sized pieces of trash on the 50 yard backstop at will. My lane neighbor came over after watching me bouce a bit of junk up and down the slope - he wanted to know who made the upper that shot so well. Then I shot his 1942 Luger (first time shooting a Luger and I am in my 50s).

    I understand the appeal of the PCC more after today - recoil is tolerable, it's much quieter than my 11.3" 5.56 upper, and muzzle flash seemed non existent.

    Andy

  6. #6
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    Quote Originally Posted by Clint View Post
    Just some advice.

    9mm builds are not as easy as 5.56.

    They can have feed problems (and sometimes ejection problems).

    Conversions/adapters/BS only make those issues worse.

    Magazine related failures are the #1 cause of issues in any platform.

    A dedicated Glock mag lower such as the FM-9 is a worthy purchase and the LRBHO is nicely executed.

    You're on the right track with the extended buffer, but that one is a single solid part.

    The FM-45 buffer is even heavier at 8 oz and has a couple moveable tungsten weights to help with bounce.

    Verify the barrel has a proper feed ramp / cone. If not, 147gr flat points and defensive ammo may not feed.

    Everything else looks fine.
    See nearby thread: My new Colt AR6951 has the problem that Federal 147 flat point won't cycle. 147 grain rounds in general are softer shooting in pistols, but that means they're less snappy than, say , Q4318 NATO 124 grain stuff. At least that's my experience.

    And the 147s jam up my Sub 2000. Maybe it's best to stick to the round nose loads on 9mm carbines.

  7. #7
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    It's not reliable with 115 or 124 gr ball atm. It ran some 124 gr standard pressure gold dot hollow points about as well (poorly?) as the ball.

  8. #8
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    I ended up going with a Spike's 9mm lower and my feeding problems were solved.

  9. #9
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    Spinta bolt, 7.5oz buffer and .308 spring and it runs flawless, never a single hiccup. This is on a QC10 Colt pattern lower if that matters.

  10. #10
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    Quote Originally Posted by locknload223 View Post
    Spinta bolt, 7.5oz buffer and .308 spring and it runs flawless, never a single hiccup. This is on a QC10 Colt pattern lower if that matters.
    I think the lower matters quite a bit and that the EndoMag is just a bridge too far with my combination of components. I may grab a lower if I find a black Friday bargain, or I may just cut my losses and build a dedicated 22 lr upper.

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