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Cotter Pins in a BCG

Discussion in 'Gunsmithing - Assembly - Finishing' started by KnotRight, Jan 4, 2020.

  1. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    I have one hell of a time trying to get the pin back into the BCG after cleaning it. No problems with a new pin. This there a trick to get the old pin back into the BCG? I tried turning it and it still will not go.

    Also, does anybody have a place to order the pins in bulk?
     
  2. Tim

    Tim I am....an enchanter. Staff Member Benefactor Charter Life Member

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    Last edited: Jan 4, 2020
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  3. 11B CIB

    11B CIB Administrator Staff Member Charter Life Member

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    If it’s not seating properly, I’ve helped them into place with a small punch from the middle/rear opening where the pin is visible. Sometimes they open up too much and you can’t get them back into place and you don’t have a spare on hand

    That KNS pin looks like a good option for a BCG that keeps opening up cotter pins
     
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  4. charliesgrave

    charliesgrave cosmoline enthusiast Benefactor Life Member Supporting Member

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  5. Pink_Vapor

    Pink_Vapor I din’t spell Thummer Wrong Supporting Member

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    I found rounding the leading edges fixes the binding.
    This pic shows one already tapered.
    CFB5359C-7224-4021-B35B-457685927F57.jpeg
     
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  6. DrScaryGuy

    DrScaryGuy Well-Known Member

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    if i can line it up just right and wiggle it up and down just right without getting any side to side motion... i don't have any problems at all.
     
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  7. Pink_Vapor

    Pink_Vapor I din’t spell Thummer Wrong Supporting Member

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    That’s what she ...
     
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  8. Burt Gummer

    Burt Gummer Nuts Over Lil D. What’s this switch do? Staff Member Benefactor Charter Life Member Supporting Member

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    Try spitting on it
     
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  9. DrScaryGuy

    DrScaryGuy Well-Known Member

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    lulz
    as Pink_Vapor mentioned, it slips in easier if it's got a good taper at the tip
    And if it's just bent, maybe you can look at having it straightened

    I had one that had such an aggressively open tip that i had to jam something inside way back up to the base and crank on it until it was back into a shape i could work with.
     
  10. Pbj ak

    Pbj ak B Supporting Member

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    The one thing my dad taught me that I actually listen to.
     
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  11. NKD

    NKD Senior Member Benefactor Kimberless Supporting Member

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    I've found the trick for me is to not look down from the top of BCG while installing pin.

    Instead, if I look at bolt face towards the back of BCG, I can see that I am canting pin down slightly and quickly line it up and it slides right in. This after many times of wanting to pound it in with a 5lb sledge! Saw this on a video and it helped me.

    Give it a try. Maybe it will help.
     
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  12. Ikarus1

    Ikarus1 Avtomat Krishna-kov

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    make sure your firing pin isn't slightly back in the bcg also helps. It's also a .02 cent part if you buy 100 spares :D
     
    Last edited: Jan 6, 2020
  13. Ikarus1

    Ikarus1 Avtomat Krishna-kov

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    Last edited: Jan 7, 2020
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  14. Hammer21b

    Hammer21b I'm you're Huckleberry

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    Take it in and out a half million times cleaning it and it’ll go in every time! That advice works for more than cotter keys! Jus sayin...
     
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  15. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    Got these in the mail today
    KNS Precision Pins.jpg
     
  16. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    I took one of my ARs out today and this is the first firing of the gun since I installed the KNS pin and after 75ish rounds the pin was backing out and locking up the bolt. Has anybody had this problem?
     
  17. Ronsc

    Ronsc LIberalism is a disease..

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    ONLY if it has been installed backwards which is usually the case with the first round fired
     
  18. JBoyette

    JBoyette Well-Known Member

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    Trim a paper clip to length.

    Once the BCG is in place it can not come out.
     
  19. 1911gobang

    1911gobang Username at Gmail....

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    Personally, I’ve never had a problem sticking it in.







    O.....M.....G...... this thread is KILLING ME!!


    To the OP, your post is legitimate, and I hope your questions are answered, but when you post a thread around here talking about sticking something in a hole....

    “Try spitting on it”......shit!!!


    Sent from my iPhone using Tapatalk
     
    Last edited: Feb 24, 2020
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  20. 1911gobang

    1911gobang Username at Gmail....

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    Just so y’all know...unsweet tea burns like hell when you blow it through your nose laughing!!

    @Burt Gummer


    Sent from my iPhone using Tapatalk
     
    Last edited: Feb 24, 2020
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  21. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    Called KNS Precision today and they said that the pins were made for the Colt BCG and that others manufactures might have a larger pin hole which would let the pin lock up the bolt after firing. On that note I went by Grainier Parts and ordered some 3/4" cotter pins to see if they would work. 100 of them for around $3.75. They should be in on Tuesday.
    https://www.grainger.com/product/5U...657acf431c32e0f0f8e0a63550f9f5a7fc877150e79ba
     
  22. Pink_Vapor

    Pink_Vapor I din’t spell Thummer Wrong Supporting Member

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    That's make me :mad:
    Their website says nothing about Colt BCG, "Replaces standard cotter pin found in the bolt carrier to retain the firing pin as in original Stoner rifles."
     
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  23. NKD

    NKD Senior Member Benefactor Kimberless Supporting Member

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    Honest question: what makes these cotter pins better/easier than a cotter pin designed for a BCG?
     
  24. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    The cotter pins that you get from Midway USA or Brownells are close to $2.00 each if I remember correctly and these were $3.76 for 100.

    At that price I hope they work. The $9 pins did not work in all ARs.
     
    Last edited: Feb 25, 2020
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  25. Ikarus1

    Ikarus1 Avtomat Krishna-kov

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    Good call on the Grainger pins. FWIW, alot of folks will argue that the cotter pins aren't 'hardened' for firearms use. Seriously. It's a steel pin. It's only job is to retain the firing pin.
    You should be inspecting your BCG in your rifle occasionally when you clean it. I do it every time I clean mine. If it looks like it's 'wearing out' then replace it.
     
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  26. Darkhorse

    Darkhorse You can bet they ain’t forgot me. Life Member

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    Had to do this just the other day.
     
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  27. BigWaylon

    BigWaylon Head philatelist Staff Member Benefactor Charter Life Member

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    I don’t need them as far as I know, but I’m tempted to order some just because. I get a discount at work and it includes free next day shipping. I can have those 100 here tomorrow for $3.10 + tax. :eek:
     
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  28. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    The new pins are a little longer which can be trimmed but the are not a thick. Not sure if that matters.
    20200225_131710.jpg
     
  29. Ikarus1

    Ikarus1 Avtomat Krishna-kov

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    doesn't look like the right diameter pin. Smash it flat on top and cut of the extra length and try it.
     
  30. Pink_Vapor

    Pink_Vapor I din’t spell Thummer Wrong Supporting Member

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    I wouldn’t trust that thin pin, it might break, or it’s thin enough that the pin might slip out past it. Both scenarios may lock up or damage the receiver.
    How much is an OEM pin? I’ve never had an issue with one.
     
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  31. JBoyette

    JBoyette Well-Known Member

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    a trimmed paperclip is a weee bit cheaper then $3.76 for 100

    ;)
     
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  32. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    @JBoyette if the pin that I bought from KNS (flared on one end) fall out or lock up the bolt how does the cut paper clip stay in the BCG?
    Thanks,
     
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  33. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    Pink_Vapor I do not have a problem usually with OEM cotter pins but when I clean the BCG sometimes I can not get the cotter pin back into the BCG. I would like to have a few around the reloading room and a few in the range bag. The KNS pins that I bought were about $7-9 each. Also, over the past 2 range trips, I have seen 2 extractors brake. They were ARs but not in 223 caliber. That got me thinking about having an extractor or 2 in the range bag too. Those are about $21 each.
     
    Last edited: Feb 25, 2020
  34. Pink_Vapor

    Pink_Vapor I din’t spell Thummer Wrong Supporting Member

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    What caliber are you breaking extractors with?
    I haven’t seen that either. I’ve been shooting the same 6.5G 300BLK & 5.56 for 12+ years.
     
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  35. KnotRight

    KnotRight Well-Known Member Charter Member Benefactor Life Member

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    Russian 45x39 (I think) and 5.7
    First time I have ever seen those calibers in an AR platform.
     
  36. JBoyette

    JBoyette Well-Known Member

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    So a few things.
    The only way a firing pin retaining pin affects the operation of a rifle is in three ways.
    1. its installed before the firing pin
    2. its too long and protrudes through to hinder the installation of the BCG in the upper.
    3. Its not captured on the left side and falls through and out the ejection port when the bolt and carrier is in battery.

    For point 1.
    I have seen many a person install the bolt, cam pin, FIRINGPIN RETAINER PIN, then the firing pin. This is the WRONG sequence. Its such a big deal DOE had it mandated all Nuclear Security officers under the supervision of a ARMOR perform this test.

    1. Place the bolt in the unlocked position.
    2. Grab the BCG with the bot facing upwards
    3. Tap the rear (buffer side) of the BCG on a table
    3a. Did the firing pin fall out?
    IF YES you installed the firing pin retaining pin too early remove, install firing pin, install firing pin retaining pin and go to step 1.
    IF NO
    4. place the bolt in the locked position
    5. Place your index finger inside the hammer track and press on the rear of the firing pin.
    6. Observe the firing pin protruding out of the bolt

    You are complete.


    To your question, clip the paperclip at a curve 1/2 way, then trim to lenght not to extend past the body of the BCG.
     
    Last edited: Feb 25, 2020
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