Accuracy Wedge?

demonsmokr

demonsmokr

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Minuteman
Aug 15, 2009
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The Lone Star State
#1
I have done a search on this site, and a google search, but with no success. I had a fellow Armalite shooter at the range over the weekend mentioned something about a wedge the sits in the lower receiver underneath the rear take down pin. He said its just to help tighten things up more, I have not been able to find out what he was talking about. Is there something out there like that for Armalite AR-10s, or was that old man a little senile? And I hope Im not over posting and crowding the forum, Im still new to the ARs and am trying to find out from actual people what I cant find out on my own.
 
#3
Re: Accuracy Wedge?

http://www.snipershide.com/forum/ubbthre...rue#Post1763832

I ordered a couple for my LR308 but it won't fit. Looks like you're gonna have to trim it to fit it. I didn't like that idea so I never used it. It's supposed to take out some play between the upper and lower. If you read the thread, some guys use a foam ear plug or larger pins to tighten up the slop which esentially does the same thing.
 
#5
Re: Accuracy Wedge?

If you have a quality AR and the upper and lower receivers are matched, then you don't need one. I have used them used on AR's that had alot of "slop" between the upper and lower and they really tightened them up. If you hold the lower in one hand and the upper in the other hand and are able to rock them back and forth an accuwedge will help.
 
#6
Re: Accuracy Wedge?

An accuwedge does NOTHING for accuracy .... the sights are on the upper along with the barrel ... if the sights move the barrel moves ..... if the barrel moves the sights move the same.
 
#10
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tyler Kemp</div><div class="ubbcode-body">No one disagrees with bedding a rifle, when the scope and action would move as one separately from the stock... </div></div>

Things that make you go hmmmm.......
 
#13
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bob L. Swagger</div><div class="ubbcode-body">If you have a quality AR and the upper and lower receivers are matched, then you don't need one. I have used them used on AR's that had alot of "slop" between the upper and lower and they really tightened them up. If you hold the lower in one hand and the upper in the other hand and are able to rock them back and forth an a<span style="color: #CC0000">ccuwedge will help</span>. </div></div>
Help help what? It certainly does not help accuracy from my experience. I don't want a super tight fitting AR that can't be disassembled without a hammer and a punch. These are a waste of money.
Pat
 
#16
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tyler Kemp</div><div class="ubbcode-body">No one disagrees with bedding a rifle, when the scope and action would move as one separately from the stock... </div></div>

That's not what you are doing when you are bedding a rifle. With glass bedding you are attempting to improve the consistency of stress placed on the receiver and barrel when torquing it into a the stock. Bedding started with wood stocks that would change pressure with the weather.

Installing an Accuwedge or bedding an AR receiver set does not even come close to the same principal as glass bedding a receiver to a stock.

HOWEVER, here is something to ponder......

The sights are rigidly attached to the upper in orientation with the barrel. They point where the barrel points. In theory this should mean that the connection between the upper and lower shouldn't matter much. However the last thing you do before a round leaves the barrel is to pull the trigger. This releases the hammer than is contained in the lower. The hammer falls and slams into the firing pin, in the bolt, which is locked into the barrel extension.

If you have a bunch of slop in the upper to lower fit, there is the possibility that the impact of the hammer could slightly misalign the upper and where the barrel is pointing at that last critical millisecond before ignition.

I don't know if it really matters, but its a logical theory.

I don't know how sloppy things would have to be to have an effect if they did at all. I know that I didn't have a problem qualifying expert with loosey-goosey M16A2s, but that didn't require sub-MOA accuracy.
 
#17
Re: Accuracy Wedge?

What I found was that (depending on how much oomph I used when I gripped the pistol grip, my exact hand position) I could throw my point of impact WAY off. At 100-200 it didn't really matter but once I started shooting prone/bipod, off bags, from different positions with my 308 it was just one more thing that could fuck me. But then mine wasn't just rattly it was wobbly as all hell.
 
#18
Re: Accuracy Wedge?

Armalite Tech Notes


February 7, 2003
TECHNICAL NOTE 55: RECEIVER TIGHTNESS
Background:
ArmaLite occasionally receives questions from customers about the tightness of the fit between the upper
and lower receivers of ArmaLite’s M-15, AR-10, and AR-180B rifles.
There is an intuitive belief that a tight fit between the upper and lower receivers is essential to accuracy,
and that loose fit is bad. Oddly enough, this is untrue.
Facts:
The upper and lower receivers of ArmaLite self-loading rifles, and all other similar rifles based on the AR-
10 or AR-15 design, are held together by two pins. Unlike rifles that are cammed or screwed together and
can be tightened, the pins allow for slight movement between the receivers.
It is possible to selectively fit pins and receivers, or to custom ream the pin holes while the receivers are
held together, so that movement is minimized. Doing so reduces the interchangeability of the receivers,
and normal wear results in looseness over time anyway. ArmaLite uses the reaming process on its National
Match M-15 rifles.
It is also possible to reduce movement by inserting materials such as paper, rubber, or epoxy somewhere
between the receivers and creating a tight fit or bind. Many commercial customers use a common rubbery
device claimed to improve accuracy, and the Army Marksmanship Unit often uses a bit of epoxy. The
AMU Armorers advise that this procedure doesn’t improve accuracy, but it makes the shooter feel more
confident about their rifle.
The AMU Armorers are correct. Formal testing conducted at Rodman Laboratories in the 1970s verified
that accuracy wasn’t affected by normal receiver tolerances. The fact is that the bullet exits the bore before
movement of the receivers produces a measurable effect.
Modern manufacturing processes are unable to produce to dimensions that both allow full
interchangeability AND prevent all movement in all cases.
ArmaLite’s rifles, except for some of the National Match rifles referred to above, are produced to military
standards of interchangeability to allow full interchange of components. Tolerances have been deliberately
tightened to reduce the movement between the receivers, but remain open enough to assure
interchangeability. ArmaLite gets a close fit between the receivers, but normal forging and machining
variations may result in a small amount of play between the receivers or slight side to side receiver
mismatch. This is not a manufacturing defect and has no effect on accuracy.
Conclusion. ArmaLite rifles are produced to tighter-than-normal tolerances. Receivers will normally
exhibit a certain amount of looseness. This is normal and will not affect accuracy. Shooters may reduce
the movement by insertion of a small amount of material between the receivers to improve the feel of the
rifle, but it won’t improve accuracy.
© 2003 ArmaLite Inc.
 
#20
Re: Accuracy Wedge?

I really don't know what to say. I have one in my 24 inch Bushmaster Varminter, but I don't run them in my carbines. I'm really not sure if it makes it more accurate, but it makes the lower and the upper feel tighter.
 
#24
Re: Accuracy Wedge?

Now I can see it might help something out in the 24 inchers. Thats what the old man had, it was a 24" custom stainless barrel. Old school Armalite too. He was kinda loose in the head I could see. But he shot great, had alot of holes real close together. But if it makes it a pain to disassemble, I dont want that. Thats kinda pointless, I dont have much slop in my gun, its all Armalite stuff, but was not matched. I bought them separate, but its still snug enough. Im still only using iron sights, so I wont be able to notice much accuracy anyways.
 
#25
Re: Accuracy Wedge?

If you or your gun shoots 3/4+ MOA groups, you will never know the difference with a loosely fit upper/lower, but you will never get a gun to CONSISTANTLY shoot 1/2 MOA with a sloppy fit.

All the TINY things are what add up to an EXCEPTIONAL shooting gun.

99.98% of the guns will not benefit from an Accuwedge (the shooter may, in his head), but all the TINY things are what is required for that last .02%

Will an Accuwedge reduce your group size 1/4 MOA?? NO, but it could be part of the intricate puzzle that builds the CONSISTANT 1/2 MOA gun.

I don't like them. If I'm building a 1/2 MOA gun, it's better to start with a proper fitting combo in the first place, but I'm also not going to say they have NO place, as they do.

PS.... and as LoneWolf said, they have NO PLACE on a defensive gun!
 
#27
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Outsy</div><div class="ubbcode-body">An accuwedge does NOTHING for accuracy .... the sights are on the upper along with the barrel ... if the sights move the barrel moves ..... if the barrel moves the sights move the same. </div></div>

i dont know about that. if your rem 700 action is loose in the stock you will shoot poorly. glass bedding is used to stop that small movement and it makes a big difference.

if you are holding the pistol grip on an ar and the upper is flopping around its not going to work correctly.
that being said. most people dont need the wedge. most recievers fit nicely.
i did see a dpms style ar10 what had a 1/16 in play in the recievers. that upper was flopping around and you couldnt get the scope to stay still.
 
#29
Re: Accuracy Wedge?

My IRA has a set screw in the lower. I just worry about it backing out, since its so small and has a nylon tip or something. Over time, that tip will take form and loose its snugness. But it does make for a very tight fit.
 
#30
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: halon</div><div class="ubbcode-body">i dont know about that. if your rem 700 action is loose in the stock you will shoot poorly. glass bedding is used to stop that small movement and it makes a big difference.</div></div>

See my comments above:

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body">That's not what you are doing when you are bedding a rifle. With glass bedding you are attempting to improve the consistency of stress placed on the receiver and barrel when torquing it into a the stock. Bedding started with wood stocks that would change pressure with the weather.

Installing an Accuwedge or bedding an AR receiver set does not even come close to the same principal as glass bedding a receiver to a stock.</div></div>
 
#31
Re: Accuracy Wedge?

For all of you disbelievers, it's this simple. The sights are attached to the upper and they go where the barrel goes. Your cheek weld is to the lower, and your hammer strike is from the lower. It only takes .005" difference in those, to throw you off by one inch @ 100. I've seen fits between uppers and lowers run almost as much as .100 off. You have to be really careful when placing your eye behind that scope if you still want accuracy. If your upper to lower fit is not tight use one. On the bag where I bought mine there is a "Trim to fit" instruction. So, if you are installing it in a defensive carbine you won't leave rubber where it can jam the rifle. You should ensure it doesn't jam on anything anyways, as someones life downrange can matter if you've installed one and didn't trim it down to fit right.

Second, if you have a "matched" upper and lower, you shouldn't need one. But if they aren't and there is play, each shot is going to bang that fit looser. Buy one for cheap, install it and have good long lasting accuracy <span style="text-decoration: underline">if you need one</span>. If you need to add body weith to get your AR shotgunned then you need to trim the accuwedge. I'll tell you this, I've found they help. But, they are not the cure-all. Just a step in the middle to solidify the upper/lower contact so you don't have to guess where to put your eye behind the sights.
 
#32
Re: Accuracy Wedge?

I have been building AR Service rifles since 1992 and i will tell you that the only thing the Accu-wedge does is make the rifle feel better by eliminating the wobble. Thats all it does. Accuracy does not come from a 5 cent piece of rubber.
 
#33
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: toolmaker64</div><div class="ubbcode-body">I have been building AR Service rifles since 1992 and i will tell you that the only thing the Accu-wedge does is make the rifle feel better by eliminating the wobble. Thats all it does. Accuracy does not come from a 5 cent piece of rubber.</div></div>

I'll agree it doesn't come from a 5 cent piece of rubber (that you pay a few bucks for). But what it does is eliminate the difference you encounter if you have a poor fit between upper and lower. I'm inclined to think since you've been building them as long as you have that you don't let them out the door with a "wobble". What that 5 cent piece of rubber does (and BTW earplugs won't work as well) is keep the difference close to the same if you have any wobble between upper and lower. This will not make up for a poor alignment between barrel and upper, poor chambering, lack of mindset when torquing barrel to upper, poor job on barrel, poor job installing front sight or flash-hider/muzzle-brake...etc. All it's going to do is hold the upper in the same position to the lower. So that when you go to pull the trigger your not dealing with mis-alignment between your eye and the scope.
 
#34
Re: Accuracy Wedge?

Even if the wedge has a certain positive psycological effect on the shooter, feeling more confident in a "tighter" gun, I do not see that it will actually do anything but that.
When looking at slow-motion high-resolution video from a shot fired and what it does to the scope,mounts,barrel and other solid steel and alu parts it is obvious that the vibrations and shockwaves through a weapon in even a small caliber like the 5.56 is more than enough to let the upper wobble around like the plastic wedge was not even there.

Even the slack created when paint or other surface treatments wear off is enough to create that wobble in an otherwise very tight upper/lower combo.

The only thing I could imagine would be able to cure this somewhat would be some kind of tapered/expanding locking pins that could be tightened as wear and tear occur, this is however not a valid solution for rifles used for anything but range activities as tools would most likely be involved.

John - out
 
#35
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: John lima_mike</div><div class="ubbcode-body">Even if the wedge has a certain positive psycological effect on the shooter, feeling more confident in a "tighter" gun, I do not see that it will actually do anything but that.
When looking at slow-motion high-resolution video from a shot fired and what it does to the scope,mounts,barrel and other solid steel and alu parts it is obvious that the vibrations and shockwaves through a weapon in even a small caliber like the 5.56 is more than enough to let the upper wobble around like the plastic wedge was not even there.

Even the slack created when paint or other surface treatments wear off is enough to create that wobble in an otherwise very tight upper/lower combo.

The only thing I could imagine would be able to cure this somewhat would be some kind of tapered/expanding locking pins that could be tightened as wear and tear occur, this is however not a valid solution for rifles used for anything but range activities as tools would most likely be involved.

John - out
</div></div>

You are missing the point. It doesn't help after the shot is fired, only before. It's strictly for consistent alignment. It does help somewhat when keeping the upper and lower from banging each other during firing. Which in the long run will help them stay aligned by not alowing so much wear. They will eventually wear no matter what you do.
 
#37
Re: Accuracy Wedge?

Enough with the arguing, I got what info i need. It helps with sloppy fitting upper and lowers. It does not help accuracy, I can understand sandwarriors perspective. Its simply, you are resting on the lower when your aiming, if there is sloppy fit between upper and lower, that will throw you off. No one can argue that, its called physics. It maybe a tenth of an inch, bu that tenth turns into whole inches further down. So, I think Im going to buy a bag just to have. Try out and see if I like it. No big deal, not something worth arguing over. Geez.
 
#38
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GoatHead</div><div class="ubbcode-body">Enough with the arguing, Geez. </div></div>

Its not arguing.. its just constructive conversation.. And this <span style="text-decoration: underline">IS</span> a forum.. its kinda whats suppose to happen. You wanna see an argument just say the .308 isnt accurate past 300yds or something along those lines...
 
#39
Re: Accuracy Wedge?

I challenge you to hold your AR so loosely that the wedge will help, all while shooting for accuracy. My mind has a hard time understanding how that would practically help in shooting...other than misplaced confidence. I bought a used AR with one installed, and it was a gummy consistency. Like a fricken wad of chewed gum. Heat? Shooting? Dunno why, and don't care to troubleshoot that, except to eliminate it. Might it never work its way into the FCG? Sure. Feel free to buy a bucket of em and replace yearly, like your smoke detector batteries. Not for me. And not arguing, just searching for Truth.
 
#40
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: carbinero</div><div class="ubbcode-body">I challenge you to hold your AR so loosely that the wedge will help, all while shooting for accuracy. My mind has a hard time understanding how that would practically help in shooting...other than misplaced confidence. I bought a used AR with one installed, and it was a gummy consistency. Like a fricken wad of chewed gum. Heat? Shooting? Dunno why, and don't care to troubleshoot that, except to eliminate it. Might it never work its way into the FCG? Sure. Feel free to buy a bucket of em and replace yearly, like your smoke detector batteries. Not for me. And not arguing, just searching for Truth.</div></div>

If you're okay with a wobbly AR then that's fine. I'm not. And short of re-bushing/pinning the bosses it's a quick cheap fix.

As far as it being gummy I would say that's because someone dumped solvent on it. I would have to agree with you there that isn't something you want inside your action. You do have to take it out if that's how you clean. ANY kind of solvent will turn them to crap in short order. Even the new citrus stuff. But, if you don't believe in them, then it's not an issue.
 
#41
Re: Accuracy Wedge?

Use a sling properly and you will not have any movement between receivers. The wedge is a perfect solution for a non-problem.
If it make the person feel good then use one. But many find it unnecessary.

As an example the standard M16/AR15 sight has a spring loaded ball to keep pressure consistent on the rear sight. It's not the issue that there is slop or movement but that its repeatable.
The fit between receivers always has some movement. If your using a sling it always pulls the receiver in the same direction.
A bipod will act similar that it always loads in the same direction.

If you have a rifle with a major mismatch TIG weld the hole closed and drill & ream a new hole for your take down pin.
I think Stoner did this on his .30 SR25's.
 
#42
Re: Accuracy Wedge?

You bring up a good point cal50. And I understand bickering is supposed to go on in forums, but it just seemed like it was going to get out of hand. And you cant pick up tones from text, so it seemed like people were angrier than I should have assumed. Ill try them out, from what you all say, Ill be going in skeptical. But if it helps with accuracy at 500yds, why not? But I can see how they may not help, but its one of those voodoo things i guess. Thats my next post, about slings.
 
#43
Re: Accuracy Wedge?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GoatHead</div><div class="ubbcode-body">But if it helps with accuracy at 500yds, why not? </div></div>

Because they can cause malfunctions.

We found a couple of rifles on the line that were having failure to feed issues. The bolt would not go fully into battery. When we broke them down, you could see the drag marks where the carrier was contacting the top of the wedge.
 
#45
Re: Accuracy Wedge?

I put one in my AR-10 years ago and it required removing a lot of material from the bottom just to get it to fit. I never did any accuracy comparision testing but the thing was such a pain in the ass that I got rid of it. The way I look at it, if these wedges were so essential for accuracy, then the would be installed standard in all the AR-10T's, DPMS LR-308's, SR-25's,POF's, ect to compensate for the tolerances between the uppers and lowers. But they're not.
 
#46
Re: Accuracy Wedge?

You argue a good point Badshot. But then again, AR-10Ts are supposed to be hand matched, and POFs are billet and I think they have the set screw, so no need there. And DPMS is just cheap, SR-25 I would expect to be like Armalite and match receivers for best fit. But your right, it probably is more of a pain to use than it would be beneficial. From what I hear it makes it a pain to dismantle your rifle for maintenance.
 
#47
Re: Accuracy Wedge?

There is nothing a $5 piece of urethane will do that practice can't.

A basic fundamental of shooting called "Follow through" is free but takes a good amount of practice to execute consistently. More so behind an AR you need to concentrate on that rather than the perceived slop in the upper/lower.

With that said... if the slop is bothering you and not allowing you to concentrate on the shooting fundamentals, then just buy it. However, you'll find that with practice and an open mind all this "accuwedge/sloppy receiver/ improving accuracy" stuff was probably never needed.
 
#48
Re: Accuracy Wedge?

Wanted to put speculation to rest.

http://img84.imageshack.us/img84/9373/accuwedge.mp4
(not sure how to embed imageshack videos)


(dots are .75")

My conclusion: Without an 'accuwedge' I can shoot MOA or a smidge better. About what I expect from myself and my AR-15. Also, not putting foam earplugs in my gun from now on. (not that I have in the past, only this time for the interests of SCIENCE)
 
#49
Re: Accuracy Wedge?

Nice post, I really enjoyed that. That being said. A piece of plastic is not worth the bickering everyone did. But your video sums it up. I dont need the wedge, I have zero slop in my rifle, just posted out of curiosity.
 
#50
Re: Accuracy Wedge?

To be a little more scientific, I did a second batch but got busy today so I'll post it now.



1: Control (no shim)
2: Accuwedge
3: Foam plug

That foam plug was doing something real wonky, I can't figure it out...

Tech specs:
556. BCM SS 16" mid length
SWFA SS 10x42 HD
69SMK over 26g of AA2520
tested at 100 yards with little to no wind

let the gun go completely cold between the two tests, and reversed the order. Shot of a bipod at the bench with rear bag support.

I have the slightest play between the upper and lower, its not junk but its not National Match grade either. For what I intend as a 3 gun comp/steel carbine this exceeds my expectations. The scope/bipod were donned just for the test as im still playing with the config but I wanted to get a baseline accuracy for the rifle as a bonus for doing this experiment.

I hope this can put the issue to rest if anyone does a search in the future, hopefully there is enough keywords in this thread for it to pop up on google and save some people money and reiterate that <span style="font-size: 17pt">you should not introduce foreign rubber objects to the interior of your rifle.</span>
 
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