PTR 9KT roller bumps
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Thread: PTR 9KT roller bumps

  1. #1
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    Default PTR 9KT roller bumps

    So was pretty disappointed today....

    I went to take apart my PTR 9KT to clean and change the stock on it, and noticed roller bumps on it. I only noticed them because when I went to tilt back the receiver and let the bolt carrier fall out, it got hung up on the bumps. Turns out they're pretty obvious once you spot them.

    This was with the original recoil spring it shipped with, with exactly 2150 rounds down the pipe (with about 750 of those suppressed). Except for the odd stovepipe, the 9KT has run very well thus far. It has been 800 rounds since I last cleaned it, and I hadn't noticed anything unusual until today. Recoil buffer had a solid imprint of the bolt carrier on it as well.

    Swapped for a new recoil spring, and it is significantly tougher to charge, so figure the original spring went soft a lot sooner than I expected. Also, with the new stock, I have a new recoil buffer on as well.

    Will test fire tomorrow, although I'm certain it'll run fine. May also change the spring on my 9C now as a precaution.

    Any fix for these? Anyone else have this issue this soon?
    I'm just hoping they don't get worse and start holding back the bolt.
    Attached Thumbnails Attached Thumbnails PTR 9KT roller bumps-sketch146183523-2_1568500704084.png  

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    Are you swapping locking peices when you fire suppressed? If not that might be the cause of your roller dents. The force of the bolt hitting the buffer is causing the bolt to try to lock and deploying the rollers into the reciever rails.

    The extra backpressure is too much, need another locking peice to increase the roller delay and bleed off the excess pressure before opening.
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    Yea definitely need to change the locking piece for sure for suppressed fire. I'd send it out to have the dents on the rails fixed too.
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    Spent most of my tax return on Hk parts, booze and ammo....the rest I just wasted

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    Was not changing the locking piece, so it seems that was the problem.

    Any way to flatten these marks myself? Anyone with an SOT that can flatten them?

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    Why would the bolt group get hung up on the roller dents when the dents are out and not in? They shouldn't affect the group coming out of the gun I don't believe.
    Regardless, very sorry to see this. It's an easy repair so don't despair.
    I don't "run" my guns or "run" anything on them. Likewise, none of my guns are "platforms". I hold them up, not the other way around.

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    My guess is the rollers extended and engaged the bumps as the bolt carrier slid back. Usually just slides right out, it got hung up long enough for me to notice it wasn't normal. Then saw the roller marks....

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    Quote Originally Posted by bangbangduck View Post
    My guess is the rollers extended and engaged the bumps as the bolt carrier slid back. Usually just slides right out, it got hung up long enough for me to notice it wasn't normal. Then saw the roller marks....
    Would you mind uploading pictures of the roller marks, I am aware of them and how they are caused, just havnt seen them for myself

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    You need to pick up a #28/80° LP for sure.
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    Quote Originally Posted by gulfstategaurd View Post
    Are you swapping locking peices when you fire suppressed? If not that might be the cause of your roller dents. The force of the bolt hitting the buffer is causing the bolt to try to lock and deploying the rollers into the reciever rails.

    The extra backpressure is too much, need another locking peice to increase the roller delay and bleed off the excess pressure before opening.
    I did not know that. Great info on these forums!

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    Quote Originally Posted by Gorrillaznyc View Post
    Would you mind uploading pictures of the roller marks, I am aware of them and how they are caused, just havnt seen them for myself
    If you look at the pic he posted you can see the dent in the rail directly above the trigger.

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