JP builds an AR

Discussion in 'AR-15 Discussion' started by Jpyle, Feb 8, 2010.

  1. Jpyle

    Jpyle New Member

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    JP builds an AR - pics added

    Ok decided to take the plunge and join the "I built my own AR" community here. Gonna start slow one component at a time.

    First up...lower. Have my eye on a receiver that R Guns has on clearance at $55. Have read that a receiver is a receiver is a receiver but is that true in all cases? Heres a pic:

    [​IMG]

    Also going with the following parts kit:

    [​IMG]

    Total cost about $130 with shipping.

    Anyone thinking these are bad choices please feel free to comment. I'll try to update this thread as I progress with the build and post some pics as I go along.

    Really looking forward to this...
     
    Last edited: Nov 18, 2010
  2. Dillinger

    Dillinger New Member

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    First off, let me say welcome to the build community, you are among friends. :D

    Second, I am the one who said that a receiver is a receiver. :p

    Here's the deal, unless you are buying from some guy named Cleatus who just got done chiseling it out of an old engine block his brother blew up in 9th grade autoshop, you are probably alright.

    Look, there are three classes of receiver.

    Cheap, chinese pot metal. Usually super cheap and definitely easy to spot.

    Aluminum, usually CNC machined and banged out in droves. Totally safe and what everyone is buying...

    Custom Machined Billet - You are paying for someone's name on the side and it's probably 10%-15% better ( tops 20% ) than the "middle of the road" receiver.

    DPMS makes a great kit, you should have zero problems....

    PM me if you have any troubles.

    SLO - You have anything to add?
     

  3. Jpyle

    Jpyle New Member

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    Getting re-engaged in the AR build as a summer project. Have acquired an upper and want to remove the existing gas block and mount either a railed gas block for removable, fold-down BUIS or permanently affixed fold-down sights. I have a few questions.

    [​IMG]

    1. What is the diameter of a Colt A1 style barrel as shown, .625. .750?
    2. Do I need a medium or low profile sight to keep below the free float tube. Are there particular measurements or numbers that refer to the appropriate heights so that the front and rear sights remain on the same plane? Maybe I am making this too complicated but how do I know the front and rear sights will line up properly?

    For example if I were to order this sight would I need to specify a height as well as a mounting diameter?

    Thanks

    [​IMG]
     
    Last edited: Jul 7, 2010
  4. Dillinger

    Dillinger New Member

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    ^^ What Slo said. :)

    JD
     
  5. mjkeat

    mjkeat New Member

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    I agree that the DPMS lpk will work and that most lowers are created = although some lowers are made from different materials and differ slightly in color (all stated above). I have heard of Sharps but have no experience w/ them. The gas block is fairly simple to remove. Some have tappered pins and some dont. For me it was a trial and error moment. Mine ended up being tappered. Personaly I like the Mbus sights used on a rail that extends past the lo-pro gas block. Thats all just personal preference though. The hooded stem is cool looking. Build what YOU want and what makes YOU happy. Because in the long run if youre not happy youll end up selling it and will never be able to fully enjoy your creation. Then again ARs are perfect for guys like me who have changing taste. Ive heard it refered to as "adult legos". Good luck Jpyle and keep us updated.
     
  6. Jpyle

    Jpyle New Member

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    Build update

    Well its been a long term project but I finally got the AR 98% completed. Went with a YHM lower and the DPMS parts kit. Completing the lower was fairly easy with only a few flying detents and one oh shizz moment when I had a spring left over. Fortunately it was only the disconnector spring so taking it apart to install the spring was not a major PITA. Note: Trigger and hammer work just fine without the spring, not sure what would have happened with the upper in place, possibly a doubler or a fully auto AR or just a trigger that won't reset :eek:

    Next up is the gas block replacement and installation of the BUIS, acquiring a decent scope and a trip to the range for a shake down...:D

    Only problem of note is a very loose rear take down pin, so loose in fact that the upper and lower separate. Will an accu wedge fix that or should I replace the pin entirely? :(

    Thanks again to everyone for the help and suggestions, it was really not that difficult and the knowledge gained was worth the extra effort.
     
  7. Dillinger

    Dillinger New Member

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    I would try the Accu-Wedge first, as it will tighten the overall fit between the upper and lower, before you go replacing parts.

    Can you post a couple of pictures of the problem?
     
  8. dog2000tj

    dog2000tj New Member

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    Pyle, I have a couple wedges laying around. if you want to try it let me know and I can mail you one.
     
  9. Jpyle

    Jpyle New Member

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    JD...Thats sorta what I was thinking, I'll take off the stock, reseat the detent and spring and see if that tightens things up a bit. I'll post some pics as soon as I can but in a nutshell what happens is that the rear pin slides freely through the upper and lower rear holes allowing the upper to pivot up and away from the lower. Can't imagine that would be a good thing while firing. :eek:

    Thanks Dog...I'll see if I can pick it up locally and let you know, appreciate the offer.
     
  10. Dillinger

    Dillinger New Member

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    Jpyle - That is not uncommon, but it is less common these days. I know that upper and know it hasn't been abused and is not a colt large pin, so we can discount that as a possible. ;)

    My first thought would an out of spec take down ( rear ) pin, as the front pivot pin fits correctly and does it's job, correct?

    An Accuwedge was basically designed to take that play out of the upper to lower receiver match. It essentially adds upward pressure to the tang that holds the take down pin, but if the pin going through is so loose it rattles, that is a point of concern for me.

    Do you have a dial caliper that you can mic the pins in question?

    An Accuwedge will run about $3-$5 at most places, so it's a pretty easy and cheap solution, but in the meantime if you want to try something to see if it will work, try a cigarette butt or a foam ear plug.
    They will essentially do the same thing.

    Now I am curious....
     
  11. Squirrel_Slayer

    Squirrel_Slayer New Member

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    I would almost think that the spring pushing the detent into the rear take down pin may be the issue, or possibly the detent itself. The Accuwedge may put enough lateral pressure on the pin to half way keep it in place during firing, but it isn't the real solution. There has to be one of three components causing the problem, and all are inexpensive. The pin, the detent, and/or the spring. I don't know that I would take the time to try am diagnose the problem as opposed to going to the gun store with ten bucks, and replace all three components. Maybe score an Accuwedge while I was there. Just my .02$
     
  12. Dillinger

    Dillinger New Member

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    I think Double S is talking about this:

    [​IMG]


    What is curious to me is that Jpyle says that the pin rattles and allows the upper receiver to separate from the lower. That makes it sound like the pin isn't large enough for the hole in the upper. With added pressure forward, from the detent towards the fire control group, it would help, but why is there so much extra play?? :confused:
     
  13. Squirrel_Slayer

    Squirrel_Slayer New Member

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    OK, I think I follow you J.D. The only real way to get all of this straightened out would be to use a small hole guage and measure the i.d. of the hole in the upper, the two holes in the lower, and then use a mic or a caliper and measure the o.d. of the take down pin. The differences of all of the measurements should be about .005" of an inch I would think. But then Pyle stated what sounded to me like the take down pin can rattle all of the way out? I guess we should wait for some pictures or more details.
     
  14. Dillinger

    Dillinger New Member

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    No, you brought up a good point S.S. Good for you thinking outside the box. ;)

    I agree it would be easy to shotgun the whole thing and fix the problem, but from my aspect, as Jpyle has an upper that I sold him, I am curious as to whether there is a problem with the receiver or with the pin.

    I know the receiver is not a large pin Colt type, it an Olympic Arms model, but I don't know about the lower he ended up with. The DPMS parts kit referenced above, if he bought that one, should be standard.

    Those pins SHOULD be about .153" or .154" in diameter and should fit both the lower and the upper without a problem.

    I am curious to see the pics as we are just guessing at this point, but I know that Jpyle is pretty good about being able to grasp the finer points, so I know it's just not him with some funky bargain bin part. ;)
     
  15. Squirrel_Slayer

    Squirrel_Slayer New Member

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    He stated earlier in the thread he ended up with a Yankee Hill Machine lower, so that ought to be the small hole take down pin type. I am leaning towards something being up with the parts kit or maybe one spring switched around. But you are right, it's all conjecture at this point.

    Just talking about this, and you're AR10 thread makes me want to build another rifle. I need a better paying job just to hang out with you guys online. Sigh.
     
  16. Jpyle

    Jpyle New Member

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    The plot thickens...

    So I go out at lunch to pick up a new take down pin and a caliper determined to figure out why the installed pin won't hold. When I get home I look over the lower and eyeball the fit of the pin to the holes on both sides, very little clearance, pin completely obscures hole, no binding on either side...ok cool not a spec problem with the lower but I'll use the new digital caliper to measure both holes, front and back just in case...loosen the stock screw, slide it off, ease out the spring, now the detent...? Where the hell is the damn detent, I know I put it in there, didn't have any parts left over. Searched for over an hour, that little sucker is nowhere to be found...friggin gremlin took it. :eek:

    So one mystery is solved and another arises...now I have to pay $8 in shipping on a $.02 part. :eek: Gonna order a dozen and springs to boot.
     
  17. Squirrel_Slayer

    Squirrel_Slayer New Member

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    You mean to tell me you don't have a single store there in NJ that sells black rifle parts??? I can score that detent at my local shop for free!!!
     
  18. Jpyle

    Jpyle New Member

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    Not a one...I had to get the lower online and the LPK and stock in Delaware. No one in NJ believes you can even own an AR and most gun shops do not stock parts...especially AR parts. I went to seven different shops in 3 different counties looking for parts and people looked at me like I was nuts for even asking.

    I'm going to order a few more mags anyway so I'll just put a field kit of emergency repair parts together...
     
    Last edited: Nov 12, 2010
  19. Squirrel_Slayer

    Squirrel_Slayer New Member

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    bummer! I can try an go get you some and mail it to you in an envelope, cost me a whopping .44$.
     
  20. Dillinger

    Dillinger New Member

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    JP - Well I hope this fixes the problem. I am happy to hear that the pin itself appears to not be the problem, which means the upper I sent you wasn't out of spec. :eek:

    I knew the thing didn't have a ton of time or rounds through it, but I honestly never thought to check if the pin holes had been worn out from constant take down and assembly.


    The offer still stands, if you need anything, let me know as I want to make sure you got what you paid for. ;)

    JD