Reader DrewR55 writes:
I have what seems to be a common AR issue. I’ve assembled a Palmetto State Armory AR-15 and the rifle functions perfectly well. But I have what is to me an unacceptable amount of play between the two halves and this bothers me every time I handle the weapon. I am ‘slightly’ OCD and the play annoys me to no end. I understand that this play does not affect the rifle in the least but it bothers so I aim to fix it. Especially because if I spend X hundreds of dollars I want it close to perfect as I can get . . .
In the case of my rifle the two pin holes on the upper are misshapen (too large) and are thus the problem. I’ve considered replacing the upper receiver but two other examples of stripped uppers have had similar issues to one extent or another and I’m tired of this game. I know I can apply an accu-wedge but I’ve heard the cheap plastic wedge can put tension on the halves and cause stress damage. I’ve purchased Armalite NM pins and they seem to solve the problem but I am concerned if they will also stress the two halves and damage the rifle like the wedge is rumored to do? Can you offer some Insight?
You’re absolutely right in that there is no impact on the accuracy of the rifle when there’s a bit of play between the halves of the receiver. The parts that make the gun “accurate” are all housed in the upper receiver, so as long as that’s solid as a rock, you’re good to go. But I understand that the wobble can be annoying and there are ways to fix that.
The wobble comes form the unfortunate fact that while AR-15 rifles have standard specifications and clearly defined dimensions – in theory everything should slide together without an issue – some manufacturers make their parts slightly smaller or slightly bigger than the specs calls for. This can lead to the two halves wobbling and the shooter being annoyed.
However, just because your gun wobbles doesn’t mean it’s out of spec. The AR-15 was designed to be serviced in the field, so the takedown pins on the front and rear of the receiver should be able to be pushed out using only your fingers. That means the two halves need to have a tiny bit of play, or the friction between the takedown pin and the upper receiver would keep them from sliding freely.
That’s what the “National Match” takedown pins our reader is talking about do. They’re slightly larger in diameter, which increases the friction between the upper and lower receiver and keep eliminates the shimmy. While “solves” the wiggle issue, it creates a new set of problems as there is now an enormous level of friction between the two halves. That puts extra stress on a relatively weak part of the firearm and could cause the pins to snap or the magazine well to crack.
Then again, just about any “solution” to the wobble will do the same thing. Increasing the pressure and friction between the two halves is the only thing that can eliminate the wobble.
The best solution, in my opinion, is the “AccuWedge” widget. Metal “national match” pins don’t have a lot of elasticity. That’s great for eliminating the wobble, but stresses the parts way more than necessary. The AccuWedge, on the other hand, is plastic. It has some elasticity and will deform under recoil to accommodate the way the gun wants to move. The halves still won’t wiggle, but you’re putting less stress on the relevant parts.
[Email your firearms-related questions to “Ask Foghorn” via guntruth@me.com. Click here to browse previous posts]