what is pin size?

Discussion in 'AR-15 Discussion' started by GREGULON, Jul 5, 2012.

  1. GREGULON

    GREGULON New Member

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    Looking for a 2 stage trigger and came across a RRA and the question of trigger pin size, a standard or long, so whats the difference?
     
  2. Dillinger

    Dillinger New Member

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    Are you sure it was standard or "long" and not "large"? Standard pins are .154" in diameter, but Colt in their infinite wisdom produced proprietary pins that were tagged "Large" at .171"

    There are anti walk pins that have been seen to be too "long" for some lower receivers. There was a set of pins that I got one time, and the "C" clip pin was a little long and caused a wobble. I don't remember the brand, but I think they were from Brownells.

    I haven't run across a situation where a longer than average pin was specifically needed. :confused:

    JD
     

  3. X-mark

    X-mark New Member

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    I believe Rock River has or used to have .155 pins, but I could be wrong. Standard size is .154. As Dillenger mentioned, Colt used to have .171.
     
  4. treehugger49

    treehugger49 New Member

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    I assembled a lower last year with a RRA LPK, and the pins are .155. No big deal. A little tighter, but a little lube and a tap and they go right in - at least in my Mega Gator lower.
     
  5. okdonk

    okdonk New Member

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    Not sure for RRA. I had mine KNS anti rotating pins size 154 for my DD and Spikes lowers.
     
  6. M14sRock

    M14sRock New Member

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    The .155s are slightly oversized (.154 is standard). That can help keep them from walking out.
     
  7. Vikingdad

    Vikingdad New Member

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    I just realized that I have a problem because I have a trigger out of a Colt with the .171" pins and installed it in my JDM lower with .154" pins. Do I need a new trigger?
     
  8. Dillinger

    Dillinger New Member

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    I believe Colt's bigger pin size were for the Takedown and Pivot pins, effectively making it impossible for you to assemble an "other" lower and slap a Colt upper on it.

    I am not a Colt expert (or fan ;)) so I can't say for certain but I do believe that they only did this on those two pins, for a short period in production time, and that it did not effect your other pins.

    As such I believe you are good to go Viking - you can always check and see if the trigger has any slop to it. If you shake the lower and it rattles like a baby toy, you have a problem. :cool:

    JD
     
  9. Quentin

    Quentin New Member

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    If the hammer/trigger pins are the large size they won't slide in a milspec stripped receiver. If they did fit you must have .154"pins from a fairly new or very old Colt.

    ETA:
    If you used small pins on the large hammer and trigger to make them fit then yes you have a problem.
     
    Last edited: Jul 6, 2012
  10. Quentin

    Quentin New Member

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    BTW, Colt went to the large pins before the 1994 AWB hoping to distinguish its commercial ARs from military/LE. Their argument was the large pin "sporter" models would not accept triggers and uppers from "evil" ARs. Didn't work of course and caused needless headaches. They went back to milspec size after the ban sunset.
     
  11. Vikingdad

    Vikingdad New Member

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    I was under the impression that the takedown pins were the only ones that differed in size, but I was wrong. The parts I have have the .250" takedown pins but the larger .171" trigger pins. I picked up some of the smaller pins at a LGS but didn't think about the trigger being the same .032" size holes (facepalm).

    I guess the question is was the receiver, having standard takedown pin size and oversize trigger pins, a rarity and if so did that make it more or less valuable? (I understand that rare and valuable are not synonyms.) It is a moot point now because I do not have the lower, just all of the parts that were stripped off of it and a description with pictures. The guy I got the parts from was hoping that the ban would be lifted in CA, but, alas, this will not come to be. :mad:
     
  12. Quentin

    Quentin New Member

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    The large pin receivers are not a rarity but they are Colt so probably are in demand at least with some people. Especially if you need a large pin mate to a receiver you already have.

    There are conversion pivot/takedown pins but I haven't seen that for the trigger or hammer pins, though the right size shim could work. I'd get a new fire control group, you don't want doubling or any unsafe condition. A standard LPK is cheap plus the spare parts are handy anyway.
     
  13. Vikingdad

    Vikingdad New Member

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    I have plenty of LPKs, but you are right, spares are always handy to have around. Have you got any fire control groups you want to let go cheap? Maybe a two-stage?;)
     
  14. Quentin

    Quentin New Member

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    Nope, don't have any spares. I bought something like 7 LPKs (DD, Stag, ArmaLite and even Del-Ton) and kept the best 4 FCGs for my three ARs and a spare LPK. I sold the others LPKs for a fair price so it worked out for everyone since even those triggers were acceptable, with the DTI the worst.

    Oh, some of the guys here have bought and like the ACT FCGs for about $65. It's a good milspec unit.
     
  15. GREGULON

    GREGULON New Member

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    Yeah yeah but what's the difference.
     
  16. Vikingdad

    Vikingdad New Member

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    The milspec standard is .154", that is what you need for the vast majority of the lowers out there, unless you have a Colt receiver with the .171" trigger pin holes. They also make .1555" pins (I have seen that Rock River makes these) which you can jam into the .154" holes which is supposed to prevent the pins from rotating I guess? but they make anti-rotating pin sets as well so I would be inclined to use those rather than an oversize pin set.

    Of course I am a newbie to the world of ARs so take what I say with a grain of salt. And those of you more knowledgeable please let me know where I am wrong.