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DPMS lower won't fit

Discussion in 'Rifle Country' started by Zakarus, Jan 10, 2013.

  1. Zakarus

    Zakarus Member

    I recently bought a DPMS lower at a gunshow and when I tried attaching my Lakeside Razorback to it the pivot holes were just slightly off, but enough that once the front takedown pin is in that the rear pin can not be inserted.

    I've searched and some people have had problems with a DPMS upper not fitting another lower.
    Has anyone had trouble fitting a DPMS lower to another upper that is not a DPMS?
    Or has anyone else got a Razorback and what lower are you using?
  2. rcmodel

    rcmodel Member in memoriam

    A DPMS lower should fit any standard upper.

    I can't say the same about a Lakeside Razorback upper, because I never heard of one before.

    Was I a betting man though, I wouldn't bet it was the DPMS lower causing the problem.

    See if you can find another name brand AR-15 they will let you try the upper on your lower and see if it fits.

  3. W L Johnson

    W L Johnson Well-Known Member

    Sure you don't have a LR-308 lower?
  4. Lloyd Smale

    Lloyd Smale Well-Known Member

    my uppers fit on my dpms lower just fine. You probably picked up a bad one and its why it was for sale at that gunshow. Some just trying to dump it.
  5. cougar1717

    cougar1717 Well-Known Member

    I had a similar issue with a separately purchased DPMS upper and lower a few years ago. If I got the pivot pin in, the takedown pin would only go partly in, but not through. There was a burr on the inside of the takedown pin hole on the upper, keeping the pin from extending through. Not sure if that may be the issue, but something to look at.
  6. JustinJ

    JustinJ Well-Known Member

    I had a DPMS lower for which it was very difficult to connect to other uppers. The receiver take down pins would just barely line up and it took far more force than should be required.
  7. USAF_Vet

    USAF_Vet Well-Known Member

    I had to file fit a DPMS upper to my ATI lower. That isn't uncommon when slapping together uppers and lowers from different manufacturers. I filed off a couple microns of metal from the rear attachment hole on the upper, and now have a tight, flush fit.

    That might be all you need to do. I suggest trying to fit your lower to another upp and vice versa just to try to pin point which part is the issue.
  8. 1911Jeeper

    1911Jeeper Active Member

    The brand name of the upper and lower doesn't really matter.

    Say for example that you have one of each with random brand names, and that they are machined correctly, within manufacturing tolerances, for pin hole locations and/or pin hole sizes. One may be at the high limit and the other is at the low limit for that dimension or pin hole size. You may have some issues assembling those two specific parts, yet both are correctly machined and within blue print tolerances.

    Reaming (or very carefully filing) the rear pin hole on the upper could be the needed fix. You may want to check with your local gunsmith before you decide make any modifications.
  9. tarosean

    tarosean Well-Known Member

    Not your typical setup, I had to google it. http://www.lakesideguns.com/

    I would suggest as RC noted, borrow a friends lower, etc and try to mount it
  10. 1911Jeeper

    1911Jeeper Active Member

    Since the upper has to fit an AR lower, the example given still holds true. One or both could be at the tolerance limits, or a pin hole is undersized.

    A simple diagnostic test would be to find another AR-15 and see if the upper fits, or not.
  11. MachIVshooter

    MachIVshooter Well-Known Member

    Not my experience at all. I have done all manner of combinations with uppers and lowers from Armalite, Colt, DSA, BCM, Rock River, Del Ton, WMD, RGuns and others. Only issue I've ever had was that some combinations produced more upper/lower wobble than others, which was easily shimmed away.

    Something is out of spec with one of his two components.

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