Pennsylvania Firearm Owners Association
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  1. #1
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    Default Spikes tactical 9mm AR pistol build issues

    Can anyone who’s built an AR9 help me out here? Im stumped.

    Specs on build:

    Spikes gen 2 glock receiver set
    Odinworks 9mm bolt (AR extractor, FA compatible, removeable carrier weight)
    Ballistic Advantage 8.3” modern series NATO profile barrel
    Odinworks Atlas9 comp 1/2”x28tpi
    7” guntech handguard
    Slash’s 9Q heavy buffer/wolff XP spring
    Standard milspec FCG (flat faced hammer)

    Finished up the build last week, went to the range for live fire testing. Loaded a single round. Dropped the bolt, aim, squeeze, bang. Ok, now we’re cooking. Loaded up 2 rounds in the mag. Bang, FTE. Cleared the failure, let the bolt drop shut to chamber 2nd round...failure to feed. Live round sitting nose up at 45* angle against the barrel. Cleared, reloaded, dropped the bolt, fed with no problem.

    This happened on every mag i ran, over about 200 rounds fired. More so on the 33rd happy sticks than the gen5 mags. The issue was still there though with mag swaps and i was not able to run a full mag thru without failures (27/33 in a happy stick went fine, 14/17 in a gen5 mag). It cycled better with 115gr ball ammo than anything else, with 124gr defensive ammo running a close second. The 185gr subsonic stuff gave me all sorts of issues, although went bang every time it chambered.

    I had a few that ejected or failed to feed that ended up sideways, one of which ended up between the bolt and the rear of the bolt catch

    I also had some issues with the LRBHO not functioning on an empty mag at times, and the bolt catch

    My first guess is bolt either to slow or moving too far due to too much buffer weight/not enough length. Second guess is that the bar for the LRBHO/bolt catch doesnt have enough spring tension to push down the follower on the mag (its pushing it down but ive had the bolt slam shut on me by itself both with and without a mag). Third guess, broken or bad bolt catch. Fourth guess, i need to shim the barrel...

    Any ideas?

  2. #2
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    Default Re: Spikes tactical 9mm AR pistol build issues

    Colt pattern 9mm AR guy here.
    Sorry, can't help with that Glock mag stuff.
    I called to check my ZIP CODE!....DY-NO-MITE!!!

  3. #3
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    Default Re: Spikes tactical 9mm AR pistol build issues

    What ammo are you using?

    I built a spikes ar9 with a spikes bolt, kak 10 oz pcc buffer, faxon barrel. No issues with close to 200 rounds from a few different magazines.

    Are you only using Glock branded magazines?

    I wonder if your bolt is too long or your buffer tube is screwed in a hair too far and you aren't getting the travel you need/short stroking.

    I don't think your buffer is too heavy. I'm using a 10 oz buffer and shot 124 grain fmj with zero trouble. I don't know if the spring is xp though. Let me see if i can find the kit i used.

    -Zach

  4. #4
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    Default Re: Spikes tactical 9mm AR pistol build issues

    https://www.joeboboutfitters.com/Kaw...eckit-10oz.htm

    Corrections, it was not kak. It was kaw valley and it DOES claim to be an xp spring.

    That said, make sure your bolt can travel far enough back to lock correctly.

    Even if your bolt catch was broken, that should have no bearing on round 2 feeding correctly. That should only matter on an empty magazine.

    -Zach

  5. #5
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    Default Re: Spikes tactical 9mm AR pistol build issues

    Was running blazer brass 115gr, seismic quakemaker +M 185gr (NATO+p+ carbine only), and a couple Sig 124gr JHP.

    Strictly OEM glock mags. The 33rd mags are new (never been shot) and have been sitting loaded in the safe for 2-3 months. couple things i noticed is that they have a little lip in front of the follower and that makes them more difficult to load into the spikes lower and dont drop free. They seem to stick a bit on the mag catch too. The 17rd gen 4 and gen 5 mags i have dont have that lip, are easier to load and will drop free.

    I’ll check the buffer tube. The bolt will travel back far enough to lock by hand. It may or may not choose to lock though on the bolt catch and i’ve had it drop shut on me without a mag in if i shake the pistol lightly.

    It doesnt feel like the buffer is hitting the back of the tube, so im not sure about the bolt being too long.

    Spikes told me that i’d need to bend the ejector a bit. Did that, it got a bit better with ejections but still kept pushing the rounds up at 45* and jamming when i hand cycled. Which leads me to it being either a mag problem or a bolt catch/LRBHO spring problem when taking into account how easily its dropped without a mag in it, and not locking up on empty all the time (~40% failure rate on empty mag

    I have a spare DPMS 308 buffer spring here, maybe i’ll pull the wolff XP spring and swap that in. Maybe the XP spring is a bit too stiff. The 9Q buffer is 8.5oz. The BCG is 14.9oz total

  6. #6
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    Default Re: Spikes tactical 9mm AR pistol build issues

    It sounds to me like you have a few separate issues. They might be fixed by the same things.

    What does the barrel extension look like on your barrel?

    Also, i missed that you said your barrel length above. It is short. You might have too much weight. Try a lighter spring or a lighter buffer. Your bolt and buffer have a lot of weight together.

    I don't recall my bolt catch being particularly sensitive. But i also didn't mess with it like that either.

    Do you know anybody in your area with a functional ar9 that you could swap bolts with and see if they run in each other's gun? Then you could rule out parts.

    -Zach

  7. #7
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    Default Re: Spikes tactical 9mm AR pistol build issues

    Quote Originally Posted by zachomega View Post
    It sounds to me like you have a few separate issues. They might be fixed by the same things.

    What does the barrel extension look like on your barrel?

    Also, i missed that you said your barrel length above. It is short. You might have too much weight. Try a lighter spring or a lighter buffer. Your bolt and buffer have a lot of weight together.

    I don't recall my bolt catch being particularly sensitive. But i also didn't mess with it like that either.

    Do you know anybody in your area with a functional ar9 that you could swap bolts with and see if they run in each other's gun? Then you could rule out parts.

    -Zach
    I think im going to start by removing the weight in the BCG first then shim the buffer setup with quarters to shorten up bolt travel. Also going to bend the LRBHO bar down a bit to put more tension on the mag follower and tweak the ejector a bit more. If no change, i’ll swap in the DPMS 308 buffer spring i have and try again. Does better with 115gr and 124gr than it does that oddball 185gr ammo.

    Barrel extension is rampless. Link to the barrel and a pic of the extension:

    https://www.ballisticadvantage.com/8...rn-series.html



    Dont really know anyone local with an AR9 built on a spikes receiver set. I did talk with one of the guys at the LGS and he told me to try different ammo and just keep shooting it to break it in. He said these 9mm AR builds are picky about ammo since they dont have feed ramps.

  8. #8
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    Default Re: Spikes tactical 9mm AR pistol build issues

    FWIW, my 357sig AR functions much better with higher energy ammo. Normal whitebox and practice ammo would FTF and FTE
    consistently, once I loaded up some "+P" rounds it was able to mag dump a 22rnd (124gr leaving the 16" barrel at 2000fps).
    I had already did the buffer and buffer spring work on it and almost gave it up as "thats just the way it is"..

  9. #9
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    Default Re: Spikes tactical 9mm AR pistol build issues

    Quote Originally Posted by 85MikeTPI View Post
    FWIW, my 357sig AR functions much better with higher energy ammo. Normal whitebox and practice ammo would FTF and FTE
    consistently, once I loaded up some "+P" rounds it was able to mag dump a 22rnd (124gr leaving the 16" barrel at 2000fps).
    I had already did the buffer and buffer spring work on it and almost gave it up as "thats just the way it is"..
    Jealous...always wanted a 357 sig or 327 federal something or other to play with. Not jealous though of how expensive it is to feed and the small performance increase over good 9mm loads

    I talked with Clint from heavybuffers.com before ordering the 9Q setup. He said i should be fine with 115/124/147gr ammo but mentioned i may run into problems with the subsonic stuff if suppressed (im not planning to can this pistol or any of my firearms until they become legal to buy over the counter like any other accessory).

    I honestly think the bolt is overtravelling for one. That would cause feeding issues in combination with a weak extractor spring. If i pull the bolt and slide a round in it and give a small shake, the round will fall out. I’ll get a donut to put under there for more tension.

    Two is the LRBHO needing bent for more tension on the follower.

    Three is my 33rd mags need the small little tab on front lip below the follower filed down a touch.

    And last thought is that the bolt just simply wont work in this receiver set and i should go out and buy a spikes bolt, waiting 12-18 MONTHS before i get it

  10. #10
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    Default Re: Spikes tactical 9mm AR pistol build issues

    Quote Originally Posted by Woodwanderer View Post
    Jealous...always wanted a 357 sig or 327 federal something or other to play with. Not jealous though of how expensive it is to feed and the small performance increase over good 9mm loads

    I talked with Clint from heavybuffers.com before ordering the 9Q setup. He said i should be fine with 115/124/147gr ammo but mentioned i may run into problems with the subsonic stuff if suppressed (im not planning to can this pistol or any of my firearms until they become legal to buy over the counter like any other accessory).

    I honestly think the bolt is overtravelling for one. That would cause feeding issues in combination with a weak extractor spring. If i pull the bolt and slide a round in it and give a small shake, the round will fall out. I*ll get a donut to put under there for more tension.

    Two is the LRBHO needing bent for more tension on the follower.

    Three is my 33rd mags need the small little tab on front lip below the follower filed down a touch.

    And last thought is that the bolt just simply wont work in this receiver set and i should go out and buy a spikes bolt, waiting 12-18 MONTHS before i get it
    https://www.joeboboutfitters.com/Spi...sp-st9bg01.htm

    In stock.

    Says it is 15 oz. But maybe the geometry is different than the Odin works bolt.

    -Zach

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