Bolt carrier jamming

Discussion in 'RFB High Efficiency Rifle' started by Revy, Jan 23, 2018.

  1. Revy

    Revy Member

    7
    Nov 12, 2005
    So I bought an RFB two years ago. A couple of days before I got to go out and shoot it, I was ran over on my motorcycle. But that's another story. Now that my hand and body are good to go, I'm trying to sort out feeding problems.

    I've gone through the gas adjustment procedures. Polished my ramp and magazine lips. Cleaned, cleaned and cleaned. I still get these weird feeding issues.

    I decided to really dig in and go over every part. That's when I think I might have found the issue. With the only the bolt carrier and the barrel (all other parts removed), I can cycle back and forth and watch the extractor lift up on ejection, and then descend back down on the inserted cartridge.

    Most of the cycles that I manually run go smoothly, but occasionally the bolt carrier will jam halfway on the return cycle. I've finally found out what causes these jams, the small lips that move the extractor up and down on the block seem to get wedged inside their channels when the block is a hair lower. Pulling the bolt back and seating the block higher will make it cycle properly. I've included pictures of the bolt carrier removed, and one where it's jammed.

    The position that it jams is exactly the same position that it sits when it has (what I thought was) feeding problems. I'd assumed up to this point that it was a magazine or ramp issue, but I'm starting to think it might be a manufacturing problem with the bolt carrier. What causes me doubt is that I cannot repeat this manual feeding issue when fully assembled. The bolt moves forward and backward using the manual lever just fine. It loads and ejects rounds perfectly. I can only repeat the problem either when fully stripped, or when firing.

    Before I box up and ship back to Kel-tec, can anyone think of anything I could try? The jamming is completely random when firing live rounds. Some magazines empty with no issues, some jam 6 or 7 times. I've ran maybe 200 rounds through the gun at most. I bought it brand new from a local gun shop, and it's a gen 2.



    https://imgur.com/7YTi4if

    https://imgur.com/D5MKieD
     
  2. flyer

    flyer Member

    45
    Nov 30, 2015
    Difficult to tell from the pics but I think I see some abnormal wear there. I'd probably send that one in...
     

  3. rb288

    rb288 Active Member

    71
    Mar 25, 2012
    Ok, I'm not sure if I am understanding your problem correctly, but.....
    1. Are you "watching" the bolt cycling with, or, without a case in the ejector?
    Without a case, the ejector will be very tight. It needs a case inserted to open it up a little, then it is free to move smoothly.
    2. Being a new gun, with only 200 rounds through it, it may still need some more break in.
    My RFB kept having intermittent cycling problems until around 500 rounds.
    Then, like magic, it hasn't had an issue since.
    I use slip2000 on the bolt and it seems to make things run smoother.
    But, that is just my gun and my experiences.
    Each one is a bit different and has it's own qwerks that work themselves out differently.
    Keep at it, stay with it, it is a great gun when you get it running right.
     
  4. Berk

    Berk Active Member

    137
    Feb 20, 2015
    I had same problem. I ended up gluing a small piece of credit card material way back in the stock to support the back of the bolt when it’s sliding forward which “fixed” this problem.
    I believe some stock plastics were slightly too spacious back there allowingnthe bolt to flop down jamming it on return.
     
  5. engineeringnerd

    engineeringnerd Member

    15
    Jan 21, 2018
    Not sure I can visualize the credit card fix. Any chance you can draw or take a picture?
     
  6. Berk

    Berk Active Member

    137
    Feb 20, 2015
    I can try but it’s so far back there it won’t photograph likely. So, with the action out and in your hand like you have pictured, operate the bolt and allow it to fall as it’s sliding forward, that’s when you experience the jam correct? Now, do the same thing but support the bolt up from gravity as if you were the plastic stock, no jam. So what’s happening is the stock isn’t high enough back where it’s actually supporting the bottom side of bolt as it slides forward. Adding some thickness there keeps the bolt from jamming.
     
  7. Berk

    Berk Active Member

    137
    Feb 20, 2015
    Here’s some info that may help. The jam is right on the corner of the receiver, right there where I’m pointing. I considered relieving that area of the receiver, but I wasn’t sure if that would help and when I tried supporting bolt better instead it did the trick so that’s better anyway. My gun runs like a Swiss sewing machine now.
     

    Attached Files:

  8. engineeringnerd

    engineeringnerd Member

    15
    Jan 21, 2018
    I had my gun apart cleaning it for the first time and wish I had read this first before I put it back together. I guess tomorrow is another day.

    I'm trying to visualize how this helps, but to be honest the RFB is so different from my other weapons that I'll need to have it in my hand to fully understand and make sure I understand where in the stock/buttstock needs to be built up.

    Thanks for posting!
     
  9. Berk

    Berk Active Member

    137
    Feb 20, 2015
    Yep it took me a while to figure it out and when I did it made me wonder if kt even knows what’s going on because my gun is only a few years old. I wonder what they would do to fix this if we sent back.

    Unfortunately I just cleaned mine or I’d offer to try and take that pic lol. I don’t clean it much anymore. Maybe every 500 or so. As a hint the piece of credit card was about 5/8” (width of stock channel) and maybe 2” Long (length of stock channel behind receiver)
     
    Last edited: Jan 27, 2018
  10. Spike Bull

    Spike Bull Active Member

    79
    Dec 14, 2017
    I have zero problems with my RFB but just out of curiosity, where did you mount the shim? On the inside of the stock, I am guessing. Did you glue it in place and how does it wear?
     
  11. Berk

    Berk Active Member

    137
    Feb 20, 2015
    Yes inside the stock, glue, it’s wearing very well. I’m wondering if it will come loose and stuff up at some point but hasn’t yet. Again, the stock is plastic, the bolt rides on the stock, credit card is plastic, it’s same same just .020” higher. I sometimes wonder if the “500 rnd mandatory breakin” procedure has something to do with this area of binding.
     
  12. Berk

    Berk Active Member

    137
    Feb 20, 2015
    Okay here’s the best attempt. You can see the edge of the credit card here. Your thickness may vary. I’m pointing to it with a poison frog dart. I think I may have feathered the leading edge a little to ensure the bolt didn’t catch the edge and rip it off.
     

    Attached Files:

  13. Spike Bull

    Spike Bull Active Member

    79
    Dec 14, 2017
    Excellent effort, Berk, very clear, thanks!
     
    Berk likes this.