Epoxy to the Rescue

After figuring out the hard way you really need to make sure you’re receiver is properly supported when you’re hammering pins in place, I have managed to epoxy my lower back together. The epoxy I used is a product called JB Weld, which auto mechanics use to fix cracked engine blocks. Hopefully if it’s good for that, it’ll hold together an AR-15 lower receiver under the impulse of repeated firing.

Lower Post Epoxy

You can see the epoxy along the seam where it broke off. I don’t really know whether the epoxy will hold the ear in place or not. The trigger guard pin would not seem to be a high stress part, but I’m pretty sure if I beat the rifle up pretty bad, it’s going to break back off at some point. As long as it stands up to normal use at the range, I won’t worry too much. It’s not like I’m going to take it into combat.

Lower after touchup

A little bit of black touch up paint seems to have tidied up the seam nicely. If you get close, you can still see the monument to my stupidity, but from a few yards away, you won’t notice. It actually shows more in LED light than it does under normal light. Really, as long as it holds, I’ll deal with the minor blemish. I’d hate to think the Pennsylvania State Police went through all that trouble to enter my lower into their registry sales record database and not end up using it to do things that make the Governor cry.

11 thoughts on “Epoxy to the Rescue”

  1. Why’d you hammer it in the first place? You could have gotten a pressing-fitting tool from the local hardware store to insert the pins.

    Can you send the lower back to the manufacturer and have them fix it or replace it?

  2. As an auto mechanic, I can attest JB Weld is great stuff. (For that matter, so is the epoxy plastic, love that stuff for when those air filter housings and other such covers crack over time.) But, would never use the stuff to try to fix a cracked block, or even a cracked radiator, unless it was like a “last V8 in the world” sort of situation.

    However, it looks as if there isn’t a lot of stress on the point where you used it (not being very familiar with ARs, I could be wrong). It appears it would hold up pretty well. Worst case, you run a few hundred or thousand or so rounds through it, realize it’s come apart, clean it off, and re-epoxy it.

    Give Fast Eddie my regards :)

  3. I used JB Weld to seal the sparker rod back into the magnesium block of a cheap firestriker I bought. The kids only had it a few hours and it fell out (before I epoxied it in). They hammer on the rod in an attempt to get sparks and it hasn’t fallen out since. The rod itself, however, is a dented and mauled thing these days.

  4. I can’t see that this is really a problem. Other than the buffer tube and maybe the cross-bolts, an AR lower doesn’t get much stress. Looking at my own AR, it looks as though a worst-case scenario is that the piece falls off and your trigger guard hangs free.

  5. You should be good to go, the pin is also holding the piece in place, and with the JB Weld it’s not going anywhere.

  6. Take a look at the pistol grip from Stark Equipment. The trigger guard is part of the grip and it covers the wings.

  7. Pingback: SayUncle » WECSOG
  8. I used JB Weld to reseat a bolt in my chainsaw. It holds my bar in place, it’ll certainly fix your cracked lower.

  9. It’d be proper and fitting if you’d cover the repair with some black duct tape.

    Sunk New Dawn
    Galveston, TX

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