AR 9mm slide slams closed with little force on buttstock

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  • AlBeight

    Member
    MDS Supporter
    Mar 30, 2017
    4,372
    Hampstead
    My apologies if this is on the forum somewhere, I searched and came up empty. I recently picked up a Rock River Arms LAR-9. When I lock the bolt open, then place it on the floor - the slide slams home. No, I’m not slamming it on the floor, the slightest hit stronger than a “diffuse an IED-type delicate pressure” will slam the bolt home every time. Also, collapsing the M4 adjustable stock fully forward slams the bolt home too. Hitting the butt with my hand relatively lightly slams the bolt home.

    While I’m familiar with the AR15 platform, the PCC 9mm version is completely new to me, and I understand the springs may possibly be stronger in comparison to the standard .223/5.56 components (???). Is this a common thing in the PCC AR? Should this concern me? Is it a problem that needs to be addressed, or simply an annoyance? I haven’t had it out on the range yet, or even cleaned it yet from brand new in box. I’m really not wanting to have to send it back to RRA already. Any advice is appreciated.
     

    danb

    dont be a dumbass
    Feb 24, 2013
    22,704
    google is your friend, I am not.
    Is this because the springs are stronger? Or not strong enough? Usually pressure from the bolt forward on bolt catch holds to bolt open. A good slam should have no effect. Could be the design of the bolt/catch, which may not have enough contact surface. This does not happen on mine.
     

    AlBeight

    Member
    MDS Supporter
    Mar 30, 2017
    4,372
    Hampstead
    That’s what I’m not sure about. I thought I’ve read where the lack of a gas system requires the springs to be stronger to make the rifle cycle. Or maybe I’m imagining I read that?? Until I impulse purchased the rifle last Saturday, I only occasionally read threads about PCC & AR-9’s and their function. What I may or may not have absorbed from those threads I wouldn’t exactly call “knowledge”. If the recoil spring is in fact unusually strong, then it seems logical there would be more force required to hold it compressed. If that device isn’t upgraded in strength or proportions too, it seems logical that the slightest bump would spring it loose. But like I said, I only have a very loose understanding of the PCC design, so I don’t want to speak from a knowledgeable base, rather an inquisitive position. I presented my “guesses” above, but hope others with actual knowledge can bring me up to speed.
     

    rfawcs

    Si Se Pwodway
    MDS Supporter
    Feb 15, 2008
    687
    Waldorf, MD
    Contact RRA. There is something wrong, let them fix it. I have a RRA 9mm upper on my home-built lower and I've never had a problem like that.
     

    DaemonAssassin

    Why should we Free BSD?
    Jun 14, 2012
    23,970
    Political refugee in WV
    Don't be surprised if RRA gives you a raft of crap and refuses to do any warranty work. I called them up and asked for some help, the dude screamed at me on the phone they were too busy to help me and don't call back, then hung up on me. Granted it was 2 weeks after SHOT Show, but still, treating customers like that is just wrong.
     

    Independence

    long member
    Jul 16, 2008
    782
    Nottingham
    Sounds like something is wrong with the bolt release. The blow-back operation requires a heavier spring, I have a 9mm ar pistol that has a 308 carbine spring but the bolt releasing when bumped is something I haven't heard of or experienced.

    I would give them a call. Until then, see if you can break it down and check the bolt catch for wear.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,815
    My Engage lower built AR9 is sensitive to hard jolts when it is locked open. I figured it was maybe a problem with the bolt catch(Strike Industry Enhanced). It's never worried me because I never store it with a loaded mag, locked open.
     

    alucard0822

    For great Justice
    Oct 29, 2007
    17,643
    PA
    Could be an out of spec bolt catch or mags with a Colt mag style. Sometimes the rear of the follower is rounded more, and doesn't push the nose of the bolt catch up that far, so nut much is holding the bolt open, so doesn't take much of a jolt after the mag is out. Could even be a broken mag catch, which is relatively common with 9mm ARs. Take the upper off, see if an inserted mag is raising the bolt catch up fully, and if the rear surface has a defect, or is flat.
     

    erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    Yeah, bolt-catches can be real finicky about tolerances on blowback guns, in my experience. Send it back to RRA and make them deal with it.
     

    Bertfish

    Throw bread on me
    Mar 13, 2013
    17,606
    White Marsh, MD
    You can make a standard AR go in to battery by locking the bolt open and then bumping the stock on the ground. Sounds like a similar issue but as you say "IED delicate" movement shouldn't cause that to happen.
     

    AlBeight

    Member
    MDS Supporter
    Mar 30, 2017
    4,372
    Hampstead
    Actually hadn’t thought of this prior to reading the replies, but it won’t do it when there is a mag inserted. Thanks to Maryland, it didn’t come with mags and I just picked up my “Pennsylvania” order from Midway. The Colt style RRA mags lock in fine, and no bolt slam - even with hitting it pretty hard on the floor. Only happens when locked back with empty magwell. Tested all of my other AR’s for comparison & none of them do it, only the LAR-9. Since this only happens with an unloaded weapon, I’m thinking I can live with this as is. I appreciate all the input given, as always.
     

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