AR-15 slop fix

[Rob L.]

Accuracy is all in the upper- since the bolt locks directly to the barrell....but If you must--- the correct part you are looking for is called an "accu-wedge"

Yup, that's what I use. Sometimes the accu-wedge requires a little grinding to fit better.

 

[Old Rooster]

Yes, most of them are pretty good right out the box but you can waste a lot of time trouble shooting it it isn't. I didn't use to do it and I had one that I found out that needed after many headaches. So now I do it with every build.

Yes, most of them are pretty good right out the box but you can waste a lot of time trouble shooting it it isn't. I didn't use to do it and I had one that I found out that needed after many headaches. So now I do it with every build.

So is that the difference between a 69.95 upper and a more expensive upper?
Or just luck of the draw?
Also how does the complete set,upper and lower machined together make a difference?

 

[6pakzak]

I've been looking up the accuwedge and xshims trying to find what results people had with them and so far I'm finding that their groups have improved after taking out the slop. I still don't get how it is that much different then a bolt gun, isn't the lower pretty much the stock, also a bolt gun has the trigger group attached to what would be the upper so wouldn't it have less need to tighten up.

 

[D2wing]

All mine are tight. But I don't buy PSA anymore.

 

[jrock]

I'm enjoying this thread.
I'm a bolt gun guy. I built an AR to see what I could do with it while applying principles of bolt gun accurizing and simple mechanics. I did a lot of things to the gun. There was a nice air gap between the upper and lower. I epoxy bedded it and its pretty slick and has held up really well. I can't say how the gun might have shot without any improvements but after load development, it shots 1/4 MOA. I was blown away that an AR could be that accurate. I've only shot 2 or 3 factory ARs with factory ammo and they were not precise.

 

[Zen Archery]

Ear plug if it's nasty accuwedge if it's ugly.

 

[NDAR15MAN]

Wedge for a little slop , over size pins for bigger slop. I have both on a few of my AR15 's. like you I do not want any movement when I put gun on my shoulder. Some people say it don't matter but I think it does when shouldering the gun. MD

 

[WildRose]

Has anyone really done a test to see the difference?

Well, doubt if you can find a university study on it but having shot hundreds of different AR platform rifles I have a pretty good idea.

The M-16 I was issued in basic was so loose it felt like it would rattle apart. The first day on the range however during familiarization I shot a perfect score with it.

I've had the same results with quite a few more.

The real problem I see with the sloppy fit is that it can cause rapid, excessive wear because of the impact forces continually eating away when the gun is fired.

Again, the biggest issue I've seen was that slop plays with your head making you less confident in your ability to shoot it which will always have a negative impact on how well you shoot.

 

[jpfrog]

I don't know about the science or data behind it- I haven't been motivated to read it because my ARs were purpose built for ranges where the difference between 2moa and .5moa won't produce a different result from what I'm seeking.

That said, I have a wedge in my AR that doesn't have the tension screw in it, the others all have the screw. I HATE noise and rattle in general- when you put it right next to my ear it drives me insane. I am certain that the distraction take my focus off my shot, making me a less effective shooter. So, not scientific, but reason enough for me to eliminate slop before I ever fire a round.

I also run silent capture devices in my buffer tubes because I cannot stand the sound from a regular spring and buffer.

I'm weird.

 

[aschler]

Thinnly, around the entire extension, as it fits /mates with the upper

I've always just used AeroShell 33MS or wheel bearing grease.

 

[aschler]

So is that the difference between a 69.95 upper and a more expensive upper?
Or just luck of the draw?
Also how does the complete set,upper and lower machined together make a difference?

For me, it has just been luck of the draw. The one that had a known issue was the most expensive upper I've ever bought.

 

[Earnhardt]

I've always just used AeroShell 33MS or wheel bearing grease.

???
No, to fill the gap between the upper/lower, install Super 33+ tape between the upper and lower surfaces

 

[6pakzak]

So thinking about it I think that the upper will probably recoil against the pins and or back of lower probably in the same spot Everytime it's fired so a little slop would probably not affect it but if resting handguard are something as opposed to just holding might change things slightly and maybe more than slightly if there's a lot of slop, from what I've searched and read .001 amount of movement would be a difference of .16 moa at 100, still not sure about it. Has anyone seen an improvement after eliminating the slop would be the question.

 

[Kansaswoodguy]

I've used the Accu-Wedge and the JP Ent. Split Rear TD Pin. Both took the slop out and both were a PITA to deal with and I've quit using them with no apparent effect.

IF the grip screw threads do go completely thru the lower (most look like they do but don''t actually go all of the way), then you can use a 1/4-28 plastic tipped set-screw from McMaster.com to lightly load the rear Take-Down pin boss on the upper. You'll need to do this w/o the grip in place, and you need to choose the length of the set-screw such that the grip retaining screw doesn't bottom out on it before the grip is tight. OR shorten the grip screw as needed.

This doesn't sound correct to me I believe a set screw ran into the grip screw hole will place pressure on the trigger removing over travel from trigger sear engagement. In essence a poor man's unsafe trigger job. I fail to see how this tightens play between the upper and lower receivers.