Getting rid of AR15 upper/lower slop , your preferred method?
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Sorry for the Ebay link. I'm lazy and this was the first hit.
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JP makes a rear takedown pin that will do it. But, it eliminates the quick take down feature of a pinned upper receiver. You can also jam a foam ear plug down there to take up the slack. I've heard of people bedding their uppers to their powers. Aero's m4e1 lower has a screw that runs up through the grip tang to put pressure on the upper. My preferred method is to remember that the accuracy in the system is nearly entirely in the upper/barrel/bolt/handguard and not worry about a bit of slop between the upper and lower. An AR that is slop free can also be a pita to take down. And, your dealing with aluminum, which will probably eventually wear into a sloppy fit anyway. I've never noticed the slop in my ar15 rifles while actually shooting- off a bench, while hunting, or on the clock. Lots of solutions to a symptom of a non-existent problem.
You can buy brass washers .001 to .002 thick and put them equally on each side of your front takedown pin. Removing that little slop will tighten the entire upper .
Those actually work quite well.
I quit using them because they were a pain to keep track of when I pulled the pins and I found tightening up the receiver fit did absolutely nothing for accuracy.
Wow...
You guys are way behind the times here, your best bet is to just not buy cheap receiver sets or ones that don't have a tensioning screw.
Here's what you need.
I'm a big fan of matched sets from the beginning. No extra stuff you don't need and you can get some very nice custom paint or coating themes if you're into those.
I use the JP Microfit pins on several of my ARs. They work pretty well. I used the extra oversized pins on my CMMG AR9. The extra oversized pins won't fit through the holes on a BCM upper but the regular oversized pins will fit.
I’ve never understood why people would think this way. You bed or securely mount a bolt action into a stock, right? Having a solid receiver to receiver fit is essentially the same thing for an AR. It helps to reduce the moving parts during the firing sequence (I.e, the barrel/upper isn’t shifting from the desired point of aim).
I`m sure it has to affect accuracy if you are precision shooting , a few thou slop on the upper can result in a miss at 600 yds , no one would entertain a bolt action rifle that wobbled around in the stock ....hence pillar bedding in bolt actions.
Yup. Works like a charm (cheap) . Or get matched pair upper / lower ('spensive)
The ultimate option to remove upper / lower slop in your precision AR is to sell it and get a bolt gun.
(radical) j/k ppl. Tho that's what I did. The AR15 is what it is.
I like a good matched set, no problems.
Reality is some times you find upper assembly's you want cheaper than you can build with a different brand of receiver.
I have a little annoying slop between my current best receivers, can feel it and hear it as I twist and pull around.
Would be easy to bed the upper with jb weld or marine tex .
But at times you may need to swap out a lower. Dedicated sets are fine till you have a failure or need to swap.
Nothing against wedges or foamies but doubt they are as good as bedding to meet OCD requirements.
I plan on using some fuel resistant gasket making material as a semi permanent bedding compound, and see how long it lasts.
If it doesn't work, last or need removed to fit a new lower a few minutes with a sharp blade takes care of that.
This is the first receiver combo that has peeked my OCD enough to try this.
Reality is some times you find upper assembly's you want cheaper than you can build with a different brand of receiver.
I have a little annoying slop between my current best receivers, can feel it and hear it as I twist and pull around.
Would be easy to bed the upper with jb weld or marine tex .
But at times you may need to swap out a lower. Dedicated sets are fine till you have a failure or need to swap.
Nothing against wedges or foamies but doubt they are as good as bedding to meet OCD requirements.
I plan on using some fuel resistant gasket making material as a semi permanent bedding compound, and see how long it lasts.
If it doesn't work, last or need removed to fit a new lower a few minutes with a sharp blade takes care of that.
This is the first receiver combo that has peeked my OCD enough to try this.
I let it rattle. I'm pretty convinced from personal experience that an AR will shoot if it has a good barrel, free floated, and a decenrt trigger. That loose fit (within reason, of course) between upper and lower has virtually no effect on accuracy. YMMV.
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X-Shims "were" the best thing ever ( lol ) for eliminating slop... but the company is gone and frankly my CC would get hacked from them.
Here is a picture of them, they came in various thicknesses... super easy to use and snug up a upper to lower.
I would "think" you could make your own out of SS shim sheets...
Youtube video shows the various thicknesses....
Here is a picture of them, they came in various thicknesses... super easy to use and snug up a upper to lower.
I would "think" you could make your own out of SS shim sheets...
Youtube video shows the various thicknesses....
The same argument is had over frame/slide fit on pistols.
Unless you’re a world class shooter, it’s way down the list.
Cheers!
Unless you’re a world class shooter, it’s way down the list.
Cheers!
Noveske (including VLTOR) KAC and LMT all make decent stuff that fits together without slop. There are others but that's what I use. Most all of the high end mfg.'s have this problem unfucked. But wanna see some funny shit, take a Mega upper or an Aero upper and try and fit that to a KAC lower --talk about some fucking slop! Somebody ain't consistently milspec here and I'm not betting against KAC...
We used to hand out accuwedges in SDM school for the students. Some hate 'em, some love 'em, I still have some but don't use 'em. Don't need 'em. Never really observed a measurable difference between M4's with 'em and M4's without 'em, but I DID measure noticeable differences between similar rifles with FF vs. non-FF tubes and collapsible M4 stocks vs. fixed A2 (SOPMOD stocks would likely be an exception).
Some things are just solutions to problems that never really existed or have better solutions already. Like receivers that fit from the factory.
Another thing you can do is go to the dealer, if that's possible, and try out a bunch until you find some that fit. BTDT too. But I'm kinda at the point now where I just build up a KAC lower and purchase a KAC upper and call it a day.
Buy once, cry once, that sorta thing.
I think I could make some of those using shim steel , glue them on and all good.
My KAC SR-15 was one of the loosest sets I’ve had. I’ve handed another (LPR) that was not particularly tight either.
I used this for mine, similar to the X-shim:
I used this for mine, similar to the X-shim:
My 4 MEGA sets are the tightest of any I've tested. Not only is there no play or rattle, they dont move at all. 1 set I received was so tight I honestly thought they were miss machined and wouldnt go together. Even emailed MEGA to start an rma.
Gave it another shot, and damn this upper had to be 100% dead straight to the lower and it was a light press fit.
If you ask me, best value/quality billet sets on the market right now.
Gave it another shot, and damn this upper had to be 100% dead straight to the lower and it was a light press fit.
If you ask me, best value/quality billet sets on the market right now.
My first AR experience was when I went through Army basic training in the summer of 1971. I was issued an M16 which remained mine through that 10 weeks. It was a loose, worn POS. I think it slopped about 1/4" side-to-side, and had about 2 inches of freebore aka totally shot-out barrel. I had shot and hunted a lot, but was used to nice wood and blued steel, and guns that didn't rattle and flop around and go boing every time I pulled the heavy trigger.
I found that my best bet was to sort of twist the grip to the right with my right hand on the pistol grip, basically cock the lower and upper against the two pins, with my face pressed against the butt and the tip of my nose touching the charging handle. I managed to qualify Expert with that worn out gun, but barely, and didn't care for the thing. I later qualified with the M-14 which I liked a lot better. When I got out of the Army I didn't have any interest in an AR for many years, but gradually found my way to the platform. I love it now.
I found that my best bet was to sort of twist the grip to the right with my right hand on the pistol grip, basically cock the lower and upper against the two pins, with my face pressed against the butt and the tip of my nose touching the charging handle. I managed to qualify Expert with that worn out gun, but barely, and didn't care for the thing. I later qualified with the M-14 which I liked a lot better. When I got out of the Army I didn't have any interest in an AR for many years, but gradually found my way to the platform. I love it now.
Drill and tap the lower receiver. 1/4 inch set screw. I think. It pushes against the upper receiver take down pin hole. You don’t have the quick opening anymore, but it gets all the slop between the two receivers out. And its still legal for cmp competitions. Hope this helps. David
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I think the Aeroprecission method of drilling up through the lower and using an adjuster screw is better as you can still take the rifle down with no tools.
Nylon Tipped Tension Set Screw
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One (maybe two) of these at the front pin: https://www.brownells.com/rifle-par...shers/ar-15-m16-receiver-shims-prod42002.aspx
Accu-wedge under the back.
Accu-wedge under the back.
Use an Accu-wedge they are 6-7 bucks at Brownells. Works great on my rifles.
Z-M WEAPONS AR-15/M16 ACCU-WEDGE | Brownells
Helps promote better accuracy by making the upper and lower receiver fit tighter. Open upper receiver; drop this long-wearing, rubber wedge into the ...
www.brownells.com
Improper milling of your own 80% lower will get your upper and lower as tight as you want.
I say improper because I don't remove as much material as the jig allows and then I hand fit the lower to the upper.
Just a little food for thought.
I say improper because I don't remove as much material as the jig allows and then I hand fit the lower to the upper.
Just a little food for thought.
Believe it or not I've had more slop in expensive lowers than inexpensive ones, KAC being the worst offender. My Noveske lower is also kinda sloppy. Aero and Mega have been the least sloppy along with Anderson which is about as cheap as they come.
Upper and lower is a rattle trap. Proper bipod load and grip pressure
Only proper way to get rid of it without sacrificing reliability is buy matched sets or buy at a store and walk around fitting them all.
Barrel to upper is FAR more important than upper to lower.
Only proper way to get rid of it without sacrificing reliability is buy matched sets or buy at a store and walk around fitting them all.
Barrel to upper is FAR more important than upper to lower.
Well that isn’t exactly true! I own a Gisselle AR15 both upper and lower! It has slop and isn’t exactly cheap!
This happens with matched upper and lowers too. I have a complete Giesselle and it has slop, not exactly cheap either. Know friends that have had the same. I have a Radian 1 that is perfect though! I have a Spikes Tactical lower with a Yankee Hill upper that has zero slop. Have a friend that has a complete LMT it has slop! So whether it’s Cheap, mid-tier or Gucci they can all have issues.Yup. Works like a charm (cheap) . Or get matched pair upper / lower ('spensive)
The ultimate option to remove upper / lower slop in your precision AR is to sell it and get a bolt gun.
j/k ppl. Tho that's what I did. The AR15 is what it is.
I run the National Match shims in all my AR's. Takes a little time to fit it, but they work great. Nice cheap little kit.
Work in large frames also.
Work in large frames also.
Thank you for showing me this. I ordered 3 kits. This seems like an ideal solution. Semi-permanent, custom fit, and more durable than O-rings or plastic shims. Amazing.
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