AR lower and upper slop fix

[drjdog5150]

So building an AR and when I put the lower and upper together it has a ton of slop. I have put plenty of these together in the past but have never had one loose before. Any ideas on a fix ?

Lower=PSA
Upper=square forge mark

Thanks to any thoughts!

Jason

 

[Seif]

For the most part there is absolutely no issue with “slop”. If it really bothers you then try an Accu Wedge.

 

[Blue109]

Cut a foam ear plug in half and mash it under the rear lug, or find a thin Oring and put it around the front lug.

 

[Elk34]

If there is a lot of slop look for another upper reciever. I do a lot of uppers and lowers. I miss match different company's lowers and uppers all the time. Some fit tight, some fit loose. If it is to loose try another upper or lower for a better match.

 

[drjdog5150]

Great ideas all around! Thanks all! And will post pics when done!

 

[outdoorplay]

I was once shown how to grind out the lower receiver around the area of the rear take down pin and fill it with JB weld. One would place in a feelers gauge of 10 thou between the upper and lower and use a tie or clap to hold it in place while the weld sets. Careful not to get too much weld in there lest it end up in places you don't want it. Also you need a release agent on the upper receiver where it comes into contact with the weld. Once it is dry one can tap the rear take down in place and eliminate play between the upper and lower receiver. This isn't a forever fix but it last longer than most.

For most people the play is not an issue. For those trying to get the most performance out of their AR for 500+ yards it helps.

 

[QuietM4]

For the most part there is absolutely no issue with “slop”. If it really bothers you then try an Accu Wedge.

Every AR mfg has different tolerances. Even mfgs that make the upper and lower to fit perfectly, they still don't make the take down pin...who knows what size that is going to be. 0.001" can make a big difference in fit.

That's why the maker of the Acu-wedge sells tens of thousands per year. And, it's why smart mfg's have a set screw under the grip tang to make the lower fit the upper.

As long as there isn't any slop between the upper and the barrel, it doesn't really matter...but the little movement will drive you nuts. And that is why I own a half dozen acu-wedges.

 

[Elk34]

I called Pacific tool and gauge and got a .125 reamer, I believe that's what it is, for the take down pin holes. I put them.together and run the reamer through and match the holes up to.each other.

 

[freefly]

If it's really bad, you can get oversize take-down and pivot pins. You can also Cerakote the lugs/mating surfaces of the upper, and/or the inside-diameter of its pin holes.

 

[Wyhs36]

For the most part there is absolutely no issue with “slop”. If it really bothers you then try an Accu Wedge.

The Accu Wedge worked great for me, I highly recommend! Good luck

 

[Man_d0wn]

I just used an accu wedge its a tight fit and requires some down pressure to get the pin back in but its rocks solid now. If tour north valley im pretty sure i have a extra one

 

[mtptwo]

For the most part there is absolutely no issue with “slop”. If it really bothers you then try an Accu Wedge.

Pretty must this. Slop is pretty normal with AR, and it does not affect accuracy one bit.

 

[Guided-miscle]

I just used an accu wedge its a tight fit and requires some down pressure to get the pin back in but its rocks solid now. If tour north valley im pretty sure i have a extra one

same experience as Man_dOwn, been using them for years, never had to replace one, works great. for dissasembly(muzzle safe direction) put the muzzle on stationary surface, pull down on the grip to relieve tension, push or pull.

 

[Elheffe]

Put a mag in it, presto

 

[Az desert rat 1]

My first build was a copy of the M16a1 that I carried in country,1972. PWA lower ever thing else Colt. Had some slop, more than I cared for, an accu wedge took care of that. Had to do some trimming on the wedge, but it worked.