Slop between upper and lower help

Maelstrom

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I have a PSA AR-10 .308 that I have use for hog hunting and plinking steel. It is not a precision rig and was not bought to be used as one. My problem is I have enough slop and play between the upper and lower than even when my bipod is locked as tight as possible I still have side to side play. I tried installing an Acuwedge but could not get the upper to closed enough to get the take down pin in. Is there any other option our idea for eliminating our at least reducing the shop between the upper and lower?
 

Steel head

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Try the little 1/4 thin washers on the pins.
works wonders but kinda a pain on disassembly and assembly
 

ricard13

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Shave the accuwedge. If it fit without shaving it then you have some major problems :) I use accuwedges on several of mine and I had to trim all of them a fair amount to work.
 
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Merle

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There is a dude that sells shims for both AR15 and AR10 but i found just building up a layer of super glue on the sides of the lugs can remove quite a bit of slop. I tried the shims and they dont stay in place very well even when glued in place.
 

DRandi

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Accu wedge is so so. It takes some slop out. O-ring around the front take down lug works better at tensioning the upper and lower, but gets cut and has to be replaced every time you pull the takedown pins.

JP sells select fit take down pins that help. https://www.jprifles.com/1.2.7_Receivers.php?menu_select=microfit

The best solution I have found is a combination of JP’s fitted takedown pins and bedding the receiver. Images sourced from the web.
1579899666597.jpeg
 
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DRandi

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Works similar to bedding a bolt action. Just google search bedding AR receiver for more info. Healthy application of Cerakote in the right spots works also.
 

striped1

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accu wedge is junk that will fail and cause your gun to lock up and not in the way you are wanting it too. JP oversize pins are the way to go. They will lock it up tight and not negatively impact reliability
 

ColoradoShooter

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Get the lower receiver drilled and tapped for an upper tensioning screw. You can buy those for less than $1 at Ace Hardware. BTW, I personally haven’t noticed any impactful accuracy improvements with a tight fitting receiver set. Granted, the upper shouldn’t be flopping over side to side but that would be obvious.
 

ScarlettRed

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The most solid approach is the ones mentioned above i.e. bedding and the accushim. Picture the receiver as a teeter totter. The takedown lug being the fulcrum pivot point. You can tighten it and push harder against it making it harder to move but the potential to rock is still there given enough force. If you put a block under each side of the teeter totter, nothing moves. My simple fix is a skinny strip of packing tape near the rear side edges of the receiver. Keep adding strips until it stops rocking. A little dab of epoxy on each side also works, just file it down til it fits. The tape lasts a long time and can easily be removed if you swap uppers. Or just leave it on the offending receiver. Usually its either an out of spec upper or lower.
 

Rocketvapor

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I believed the red rubber Kool-Aid, Accuwedge, for a while. Properly trimmed is felt tight.
It's the firing load that will still rock a soft plug. You won't feel it, but it's still there when you fire.
Something that will resist movement during firing is likely best.
A single point under the tack down lug would help.
Just like a monopod helps.
 

Tono

And...
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I used this on an AR-15.
Do they make something like this for an AR-10?
From the “Questions” page on: https://ar15accushim.com/questions.htm


Will the shim tighten .308 upper receivers?
The shim does tighten .308 receivers that have the AR15 upper receiver recess/sear relief dimensions shown on the Installation Basics Page.​
I recently added this aluminum shim to my AR. It took a while to fit the shim, as sanding/removing 0.001 of material and testing for fit is a tedious process. Especially when you want the best fit possible.

I’m very happy with the results. There’s no play between the upper and lower now.

Given that this is a custom fit, you are able to choose how tight the pins fit in the receiver. For a looser fit, one where you can push the pins out with the tip of your finger, simply remove a bit more material from the aluminum shim.

At $7.69 per kit (shipping $2.86) it’s great option/solution.

https://ar15accushim.com/ar15accushim.htm

Installation Basics
For Rifles And Stripped Receivers.
..Tightens Loose AR15 Receivers
Follow Instructions Provided In The Kit.
Average first time installation for a rifle
is 30-40 minutes. Additional rifle
installations average 15-20 minutes.
....
....

Installation/Fitting Requires
Gunsmithing Skills.
....
....
Some Colt upper receivers do not have
the machined relief. Check recess/sear
relief for .090" depth. Relief/recess
width: 750" to .755". Shim fits &
works in most upper receivers.
.....
.....
Gauge Receiver Play: Lay a blade type
.012" automotive feeler gauge across
lower receiver above the safety lever.
Close and hold the receivers together
firmly. If the pin resists when pushed
or meets resistance passing through
the receivers means the shim should
work. If the pin passed through the
receivers without resistance means
the shim may not work.
.....
.....
Place one side of the shim against the
recess wall, push the opposite
side down into recess.
.....
.....
The shim is fully seated, surface is level
and parallel with the sides of the upper
receiver. The angled ends are for
shim removal with a screwdriver.
.....
.....
Close and hold the receivers together
firmly. The bore in the upper receiver
lug should appear to be .003" to .007"
above the bore in the lower receiver.
Faint white curve is the bottom edge
of the bore in the upper receiver lug.
.....
.....

Remove the shim from the upper
receiver. Note front, middle and
curve thickness. Remove backing
from the Shim Gripper Block.
Align and press the long side of
the shim against the adhesive.
.....
.....

.
Place Gripper Block against sanding
strip. Remove .001" from the shim.
After surfacing lightly sand the edge
around the short side of the shim.
.....
.....

.
Install shim, hold the receivers together
firmly, check pin travel. If necessary
remove the shim and surface again.
Progress Slowly, Do Not Force
The Takedown Pin.
The slot in an uninstalled takedown
pin must align with the spring and
detent bore in the lower receiver.
.....
.....

.
The shim is surfaced gradually until
the takedown pin pushes smoothly
through the upper receiver lug
bore and enters well into the lower
receiver bore as shown above.
.....
.....

The remaining short portion of the
takedown pin can be seated with
the supplied driver. Tap the driver
with a screwdriver handle.
.....
.....

Takedown pin is fully seated and
the receivers feel Rock Solid.

Follow Instructions Provided In The Kit.​
 

KaRwithaScar

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Shave the accuwedge. If it fit without shaving it then you have some major problems :) I use accuwedges on several of mine and I had to trim all of them a fair amount to work.
I agree with you...if you dont have to shave the accuwedge a bit thats a problem lol. I always do
 

shoobe01

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The guns I have an Accuwedge in I just push harder. It's elastomeric, so that works. Done to a few other guns also when they couldn't install. Just push the upper and lower together while pushing the pin out.

One of my FALs and the SIG 55x are also tight enough metal to metal I need to do that to get their takedown levers/pins to release sometimes. Seems valid.
 

acudaowner

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we saw and tried this first and it worked to a degree the wiggle mostly stopped but the bands broke a lot thank god they were only a few cents per hardware store washers eventually choosing a fix that would last forever removing the push pin and using a tiny bolt and a nut 35 cents to fix . the excessive wiggle stops but I have to remove them to clean not a big deal to me .good luck on which ever way you go with yours .
 

Yondering

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I already gave it. Find the right size takedown pins.

You would be surprised at the variance by manufacturers of LPKs and pin sets. Also why I always reccomend match reciever sets.
Just stop, dude. Different takedown pins are not the answer to most upper/lower receiver play.

Even on matched receivers, bedding can often improve the fit, and is a big improvement in normal upper/lower fits unless you get lucky with a tight set.

The O-ring trick works too, but as pointed out above they need to be replaced often. I've switched to just using an O-ring to stabilize the receivers during bedding with "ultra black" RTV. Once the bedding is dry, the O-ring can be removed and the solid fit remains. I do this to all of mine now.
 

Rocketvapor

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I would probably agree with @2aBaCa if I had ever bought a premium matched receiver set.
I'm sure for the money I would really be pissed if they didn't fit perfect.
Can you buy a 3 or 4 piece matched set? 3 uppers all matched to one lower?
Or are you stuck with a matched set for every purpose?
Maybe a .223, a .224V, and 22 Grendel upper?

You could always ream the holes to match an oversize pin and get at least a good one point fore and aft fit relying on the upper to hold everything together nice and tight. Maybe save that to correct wear.
Bedding does sound like an option but making it pretty around the edges where it might be seen takes skill :)

The soft approach with the wedge feels tight but is it really? When things go bang does the wedge give?
Does it give with a heavier F-Class gun?

I have a couple uppers that I like to fit to one lower, all set up for prone 600/1000.
I can fit each upper to that lower. They also fit some of the others but not all.
Each has it's own scope.


If it wasn't for the AR-Lego aspect, I'd probably be more into bolt guns.
 

2aBaCa

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I would probably agree with @2aBaCa if I had ever bought a premium matched receiver set.
I'm sure for the money I would really be pissed if they didn't fit perfect.
Can you buy a 3 or 4 piece matched set? 3 uppers all matched to one lower?
Or are you stuck with a matched set for every purpose?
Maybe a .223, a .224V, and 22 Grendel upper?

You could always ream the holes to match an oversize pin and get at least a good one point fore and aft fit relying on the upper to hold everything together nice and tight. Maybe save that to correct wear.
Bedding does sound like an option but making it pretty around the edges where it might be seen takes skill :)

The soft approach with the wedge feels tight but is it really? When things go bang does the wedge give?
Does it give with a heavier F-Class gun?

I have a couple uppers that I like to fit to one lower, all set up for prone 600/1000.
I can fit each upper to that lower. They also fit some of the others but not all.
Each has it's own scope.


If it wasn't for the AR-Lego aspect, I'd probably be more into bolt guns.
If you get them all from the same manufacturer your usually good to go.

Just stop, dude. Different takedown pins are not the answer to most upper/lower receiver play.

Even on matched receivers, bedding can often improve the fit, and is a big improvement in normal upper/lower fits unless you get lucky with a tight set.

The O-ring trick works too, but as pointed out above they need to be replaced often. I've switched to just using an O-ring to stabilize the receivers during bedding with "ultra black" RTV. Once the bedding is dry, the O-ring can be removed and the solid fit remains. I do this to all of mine now.
You would be surprised. Its magical.

All these other methods are simply pushing the recievers apart until it pinches the small pin.

And yes I dare to say the right size takedown pins are the solution to a most upper/lower receiver play.
 

Yondering

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You would be surprised. Its magical.

All these other methods are simply pushing the recievers apart until it pinches the small pin.

And yes I dare to say the right size takedown pins are the solution to a most upper/lower receiver play.
No, I wouldn't/wasn't surprised, because I'm speaking from experience. Maybe you've only had receivers with very minor play between them. On typical mix & match receiver sets, the only way to make a pin set fix the issue is if both holes are reamed for oversize pins with the upper and lower held together during the process. Then of course those won't fit any other upper or lower.

A lot of loose upper/lower fits have a lot more play than you may realize. When you can see a sliver of daylight between the upper and lower with the pins installed, tight tolerance pins can't fix that. Bedding the upper or the lower for full contact between the two gives far more support and doesn't wear loose again.
 
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Nimothy

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Anybody have a tips to properly install a muffler using dry cleaner wire hangers?
Idk about properly but my first car was a 67 ford galaxie and it took just about my whole 16yrold paycheck to keep gas in it, I’m pretty crafty with a wire hanger zip ties and a pair of piers. So if you send pics I can probably get you out of a jam. I once coat hangerd the muffler on that car and it stayed up for over a year until the motor gave out again (I was 16 and had a heavy foot)
 

Yondering

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To each his own. Use bubble gum and duct tape if you want.
Good for you, if you'd rather use a half hearted solution that doesn't really work, have at it. :rolleyes:

Personally I can use whatever solution I want and have the skills and tools to do it. I choose to bed for full contact between the upper and lower for the best fit possible.
 
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Dolomite_Supafly

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The easiest and cheapest way I have found to fix it is to us a hot glue gun. I clean the lower at the rear take down pin really good so the glue will stay in place. I wipe the corresponding upper area with very light film of oil. If the gun has already been shot it will be fine without more oil.

I use a hot glue gun and put a blob where the upper will seat into the lower then I close the two, push the pin in and wait a few minutes.

This gets rid of 100% of the upper/lower slop. Gets rid of any up/down slop as well as any side to side slop. It is reversible and only takes a few minutes.
 

19Scout77

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What a bunch of redneck engineering! Bedding receivers...ear plugs...hot glue. Here’s a novel concept...buy parts that don’t suck. Over dozens and dozens of ARs built owned and played with I have NEVER needed any of these assine bush fixes.
 
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SFree

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What a bunch of redneck engineering! Bedding receivers...ear plugs...hot glue. Here’s a novel concept...buy parts that don’t suck. Over dozens and dozens of ARs built owned and played with I have NEVER needed any of these assine bush fixes.
You sweet talker, you...
If it’s a hog rifle proven successful, why worry? Otherwise, sell it and get quality parts as Scout said. Parts are listed frequently for sale at great prices, better yet, buy a quality rifle at wholesale prices...
 

Rocketvapor

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I agree. Buy quality stuff and you won't have these issues.
.1 mil costs money.

Go cheap, post on the cheap forum, not SH :)
My $1000 rig (Bipod and optics included) just don't compete with the high end guns.
 

Maelstrom

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Well I tried the oversized JP pins and that didn't fix the problem. It actually created a new one. I had to use a delrin punch to get the rear pin out. It won't pass through the upper without a lot of force. I am going to try to bed it and see how that works. The rifle has proven more than accurate enough for what mouse it for. I didn't buy it to be a competition gun but to a cheap hog blaster and plinker.
 

Yondering

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Well I tried the oversized JP pins and that didn't fix the problem. It actually created a new one. I had to use a delrin punch to get the rear pin out. It won't pass through the upper without a lot of force. I am going to try to bed it and see how that works. The rifle has proven more than accurate enough for what mouse it for. I didn't buy it to be a competition gun but to a cheap hog blaster and plinker.
When you bed it, temporarily put an O-ring around the front upper lug, as shown in the pic below. That springs the upper and lower as far apart as possible, so that when bedding is complete (and the O-ring is removed) you have the tightest possible fit. If you bed with black RTV (the toughest kind) this way, you get a very solid fit but can still install and remove the pins easily. This is how you get an upper-lower fit with zero play/movement/rattle.

 

bfoosh006

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Ya know.... I bet people said the same thing to folks supping up their old Fords, Chevy's and Dodge's.
Or fixing stuff themselves... at home.

Porting heads comes to mind.... your time, your effort, can produce improvements.... swapping cams.. intake manifolds...

I realize... according to some in this tread, those motorheads should have bought a Corvette ..... instead of their Chevelle.

But.

Self reliance should be something to be proud of... not made fun of.
Not all of use can afford every upper and lower be a work of art and perfection.

.

You don't have to have the "best" , more expensive parts to produce respectable numbers.



Sometimes your time can help produce the advantage desired. And more people should tell others to give it a try .

Some people just have tell everyone else how wrong they are.... instead of just offering help, they have to be "right"... and you have to be wrong.


In this case, IMHO, bedding and / or shimming can help. And I suggest the OP go for it.

FWIW... I have used the old "X-Shims" to snug up fit... sadly they are not made anymore. The X-Shims worked great.

So if you are capable, and don't feel like buying a different lower or upper... look up some of the videos on youtube , and order some .002-005 plastic shim stock off Amazon , and cut some for yourself.


And before someone says upper to lower fit doesn't matter.... I suggest you look up the actual US Army report, and actually read it.
Not just quote it.
You are going to find it isn't as conclusive or decisive as you'd think... at all.
 
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Yondering

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You can take the fool out of ARF.com but you can’t take the ARF.com out of the fool.
The only fools (or the other word you used prior to your edit) here are the two guys with apparently more money than sense who want to look down their noses at the guys who actually know how to improve their rifles. You've contributed nothing of any value to this thread; why are you even here?
 
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hlee

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So I've got a couple of rifles with somewhat sloppy fit. I also have a glue gun... Well, a bit of oil on the rear upper receiver mounting support (and a good wiping down of the lower receiver to remove any oil) and a blob of glue down in that recess. I also put an index card between the upper and lower, near the front take down pin (as a wedge), while the glue was cooling. The index card was just enough shim to make the rear take down pin slightly difficult to push home. On the rifles this was done to, the slop is not totally eliminated, but it is so much reduced that they feel like different guns. Has the accuracy improved? Probably not, and I've only shot one since the mod. But, the rattle is gone. I didn't care enough about the slop between the receivers to do anything about it before I saw this thread, because they all shoot really well. When someone suggested the hot glue gun, that was an idea that is sufficiently easy, cheap, and reversible that I thought "What the hell, I've got a few minutes." I also didn't risk gluing my gun together permanently with bedding compound. Well, it works, and I can still easily open the rifles without tools. This is not something that can be said about over-sized pins, tensioning screws (one of the rifles is built on an Aero M4E1 enhanced lower), or other bits of AR15 "magic."

Yes, I could have replaced the uppers and lowers with units costing several x the money. (For rifles that already shoot really well? Talk about throwing good money after bad.) I could have bought accuwedges and pins and other bits and bobs that would eliminate the slop. But, the glue gun was sitting in the garage. And, if I don't like it, I can pop that little glue pad out of the lower with no wear to me, the rifle, or my wallet.

If you've got a glue gun, a rifle with some sloppy fit you'd like to tighten up, something to use as a wedge while the glue cools, and 20 minutes to kill. Go for it. If there is a best part==> If you try it and you don't get exactly what you are after, add more glue to the pad and go again. It only takes a few minutes for the glue to harden. Build the pad up iteratively. But, don't expect magic. This won't make your AR15 feel like a bolt gun. There will likely still be a bit of play. But, I don't notice it on mine unless I torque around on the rifle.

I have one AR15 that exhibits the proverbial "bank vault" fit between the upper and lower. It's built on a mis-matched Anderson upper and lower...