PDA

View Full Version : AR-15 upper and lower wobble fix question


epic4444
February 9, 2010, 01:48 AM
Hey, thanks for looking, so i just finished two AR builds, one with a Mega Lower with a LMT upper, rock solid fit. The next was a Mega Lower and Noveske upper, not nearly as solid, there some wobble or slope between upper and lower. Ive read online that people use #7 o-rings to fix this, anyone have a video or tutorial on how to? or even some pictures would be awesome since im confused about where the ring goes. Thanks

NSO_w/_SIG
February 9, 2010, 06:14 AM
Why worry about it unless it is malfunctioning? "Wooble" has no affect on accuracy.

jmr40
February 9, 2010, 08:45 AM
Try installing an accuwedge. Midway sells them for around $4. It is a rubber wedge that fits between the upper and lower than tightens things up. Probably has no effect on performance, but stops the wobble.

AK103K
February 9, 2010, 09:06 AM
The "O" ring goes on the front lug, and it does work. I have a Bushmaster that has the same problem and it always drove me nuts until I found this cheap and easy fix. I also had to make my own oversize "accuwedge" out of a drafting eraser for the rear.

http://home.comcast.net/~jesse99/AR_Wiggle.html

look close at the base of the lug, you'll see the "O" ring...
http://home.comcast.net/~jesse99/o-ring1.jpg

brian923
February 9, 2010, 12:44 PM
i have always wondered if wobble has "no" effect on accuracy... not trying to start anything, or call anyone dumb or stupid, but i always hear this. i have an AR that is very tight. almost annoyingly tight, but i would rather it be that way then loose.

my thought is that, a tighter upper to lower fit would be more accurate at longer ranges. heres my thinking....

everyone knows that consistancy is one of many keys to accuracy. harmonics are a BIG part of consistancy. barrel harmonics are the biggest factor in all around rifle harmonics. for those who may not no, if you change the harmonics of your barrel for instance, you can shift your point of aim, tighten or open your groups and so on. SO..... my thought is this...if the upper to lower fit changes overall rifle harmonics from shot to shot, this in turn can change barrel harmonics and shift bullet impact, thus having a great impact on overall accuracy.

is it right? i have no clue. just wanting to see what others thought.

brian.

AK103K
February 9, 2010, 12:55 PM
I think your right, and that it does affect accuracy. The consistency isnt just with the gun either, its also a combination effect of rifle and shooter.

For me, just the distraction of the movement is enough to affect it. We are always the weakest link in the equation, so why aggravate it even more?

I know its not supposed to be an issue, but I'd like to see how many match or precision rifles have play in them, or at least enough play to be noticeable to the shooter.

NSO_w/_SIG
February 9, 2010, 03:10 PM
There is a long thread on ar15.com that talks about this topic, I am not going to look it up but if you have the desire it is out there. Lots of good information. Come to your own conclusion, but after reading it, and the links contained within in it. I have made up my mind that it has no noticeable effect on accuracy.

Bird is the Word
February 9, 2010, 03:11 PM
Accu-wedge worked for me, but that and/or O-ring and don't worry about it further.

Any accuracy issue would like be practically speaking negligible.

Ridge_Runner_5
February 9, 2010, 04:40 PM
I use a squishy earplug under the rear take down pin...no movement whatsoever.

80viking
February 9, 2010, 06:20 PM
I believe all the accuracy is in the upper, but having a tight AR does help the shooter, which in turn helps accuracy.

LongRifles, Inc.
February 9, 2010, 07:57 PM
Just shoot it.

gotigers
February 9, 2010, 08:34 PM
I use a squishy earplug under the rear take down pin...no movement whatsoever.

This works.

Hey, Ridge is back. :eek: :cool:

chasep255
February 9, 2010, 08:42 PM
Try this... http://www.midwayusa.com/viewproduct/?productnumber=698479

pilpens
February 9, 2010, 10:48 PM
IMO, the upper and lower slop has to negatively affect the accuracy of a rifle. Because of the slop, the rifle will behave differently during recoil everytime it is fired.
Seems like it would equate to a bolt action rifle with loose action screws.
How much?

Ridge_Runner_5
February 9, 2010, 11:25 PM
This works.

Hey, Ridge is back.

Nobody can ban me forever:D

TheManHimself
February 9, 2010, 11:30 PM
USAMU says it has no affect on accuracy. USAMU knows a hell of a lot about what makes a weapon accurate. USAMU also says that if taking the play out of the receivers enhances the shooter's confidence in the weapon, it may increase the shooter's ability to make good hits. So yeah, it's a cosmetic issue. A "fix" won't affect the inherent accuracy of the weapon, but may provide a psychological boost to the operator. People spend lots of money on other weapon modifications that are just cosmetic in nature too - high-grade walnut stocks, nigh-invulnerable epoxy-based metal finishes, custom engravings, fake cans, jeweled bolts, etc. Bottom line, if it bothers you, stick something in there to take up the play. If you can accept that it doesn't matter, it really doesn't matter.

gotigers
February 10, 2010, 07:45 AM
FYI, the accuwedge does not work in some ARs. They dont work in my S&W. The shelf is much higher and the accuwedge just doesn't fit.

AK103K
February 10, 2010, 09:19 AM
I had the same problem with my Bushmaster. Its why I made my own out of the white rubber drafting eraser.

Double Naught Spy
February 10, 2010, 09:59 AM
The accuwedge worked great in my old Colt 6920. It rattles whereas my other Colts don't.

However, I like the cheapo washer idea. That looks very promising.

epic4444
February 10, 2010, 11:57 AM
Ya, im not doing it to be more accurate, i just want a more solid feel to the rifle.no reason to have the wobble if it can me eliminated right? thanks everyone

The Tourist
February 10, 2010, 12:09 PM
Epic, I just checked and I still have a red-rubber wedge in my gunroom. If you cannot find one, contact me and I'll mail it out to you.

But what you have heard is correct, it makes no difference on accuracy. I removed mine from a hand-built varmint rifle because it was more difficult to field strip and the wobble was minor.

Col. Jeff Cooper would call this an "ingenious answer to a nonexistent problem."

AK103K
February 10, 2010, 12:39 PM
I'd be interested to see what type rifles were being tested, and how they were being shot, when the "no difference" results were declared.

I understand the theory behind the upper/barrel/sight relationships, but that doenst take into account the variation between the cheek weld/rifle mount and the uppers movement in relation to them while the rifle is being shot, especially in rapid fire strings on a target range, or anywhere else for that matter.

How many of the target/precision shooters out there have guns with slop in them? I'm thinking not to many. I know I wouldnt stand for it if it was my rifle, and I normally dont with any of my AR's, precision or otherwise. Its the reason why my Bushmaster has the mods to it.

Interesting enough, my Bushmaster is also the least accurate AR I own. Now is that due to something else, or the slop in the fit, I cant say, but my Colts, and Armalites, never had any slop in their fit, and all shoot considerably better than that Bushy.

tirod
February 10, 2010, 02:16 PM
"shoot considerably better" That right there is the problem, most information is anecdotal and a sample of one. No measurable way of quantifying that.

The United States Army Marksmanship Unit is a precison shooting team with decades of experience. They made the switch from M14 to M16. Their short answer is they tried it, it made no difference. IF it had, everyone on the circuit would be all over the "Answer" and tell us exactly what MOA improvement it would be to the .100." Since that hasn't happened in the last 25 years, oh well.

Feel free to write the commander and request the data/survey/paper describing the exact conditions and results. Don't expect a quick answer.

Or, feel free to ask on an AR forum where industry professionals participate. Be prepared to hear the same answer, because that's where the info is coming from, to whit, they tried it too, didn't make a difference, and their buddies on the USAMU agree.

Barrel resonance during the propulsion stage is what causes the muzzle to vibrate, and IF the barrel is documented as X MOA characteristics, it can be tuned to a node so the muzzle isn't moving . It's exactly what the movable weights on target rifles are for. Browning sells a device, too.

Slop in the upper/lower fit won't be there as you fire it, because of the cheek weld, grip, forehand, and stock touch points, much less any sling tension. If that isn't consistent, it's shooter error, not a firearm fault.

Military firearms are built differently, don't automatically infer bolt actions on a wood stock set the same rules.

AK103K
February 10, 2010, 03:08 PM
"shoot considerably better" That right there is the problem, most information is anecdotal and a sample of one. No measurable way of quantifying that.
Same goes for all the other responses, so short of any document of any real merit that "proves" it, we're all in the same boat, everything is anecdotal.


Slop in the upper/lower fit won't be there as you fire it, because of the cheek weld, grip, forehand, and stock touch points, much less any sling tension. If that isn't consistent, it's shooter error, not a firearm fault.
I understand what your saying here, but still, if there is slop, no matter how well your slung in, the slop is still going to move as you and the gun move under recoil. If there is slop, there cant be true consistency. Is it enough to matter? I dont know, I suppose that will depend on the amount of slop and the shooter.

The pro shooters are not drawing and shooting a rack grade gun that may or may not have some slop in the fit. I'd be very surprised if there was ANY perceptible slop or movement of any parts in their rifles that arent "supposed" to move.

Volucris
February 10, 2010, 06:01 PM
All attempts to remove the play are futile. Does not affect accuracy of the rifle nor its function. There is SUPPOSED to be some play so you can disassemble the rifle quickly. The rifle is not even designed to require perfect fit.

tirod
February 10, 2010, 06:44 PM
The sights are attached to the barrel. If it does move, it changes your sight picture, you compensate, then pull the trigger. You are still shooting the barrel and the attached sights.

Does it move after you shoot? All weapons recoil, that can't be stopped. What is worse, a 1/16" rattle or a 2" muzzle jump? Doesn't make a difference, because the recoil impulse is more than any side to side variation and controls all movement at that point. The bullet traverses the barrel and exits long before there is muzzle rise, anyway.

Take the so-called lock time of a trigger into account. Loose upper or otherwise, as a shooter bobbles about on the target, a fast lock time is supposed to cut down on movement off target and reduce error. The only shooters who see an improvement are out beyond 800 yards. It's miniscule.

Milspec M16/M4's shoot 2 MOA - 2 inch groups at 100 yards. Even at 600 yards, that's a 12 inch group, plenty accurate enough to hit a man sized target. And those are loose, rattly M16's and M4's. The agonizing over a loose upper to lower fit is not based on any science, it's a perceived quality issue based on marketing. No, good shooters don't prefer loose stocks, but it's more a tactical application, not a marksmanship question. Military firearms still come apart, unlike most all other precision rifles, and some tolerance stack must exist - or you have to beat the pins out to clean it.

Those who have shot military rifles know this, those who haven't, don't have a clue.

Double Naught Spy
February 10, 2010, 07:24 PM
All attempts to remove the play are futile. Does not affect accuracy of the rifle nor its function. There is SUPPOSED to be some play so you can disassemble the rifle quickly. The rifle is not even designed to require perfect fit.

In all my reading on the platform, I never came across anything to suggest that there is supposed to be play between the upper and lower for quick disassembly. Quick disassembly is accomplished via the take-down pins.

Volucris
February 10, 2010, 10:25 PM
...which are easier to remove if they're not being strained to keep the upper and lower super tight

tirod
February 10, 2010, 10:32 PM
And having unboxed new M16A2's, they just push out. A little stiff, but I could thumb them. Others report on builds having non matched uppers and lowers which required using a light hammer tap to separate.

NOT good on the firing line, ask anyone who's trying to rod off. Worse in the field. What ya gonna use, a rock? No, fix the problem, loosen the pins and fit.

Uppers and lowers do NOT have to be tight. It's not milspec to hammer the pins out. Those WHO HAVE SERVED and shot military weapons know this.

Anybody?

80viking
February 11, 2010, 01:14 AM
Look at it from another prospective. Lets compare the basic match AR design to a very accurate bolt action varmint rifle. Some of the things that contribute to a bolt actions accuracy are glass bedding for the receiver, a one piece stock carefully torqued to the receiver, and the barrel, receiver, and trigger all homogeneously mounted to the same platform. I think the only thing that the bolt gun and the AR may share would be a match grade barrel, and a free floating barrel.

Now we all know how accurate both these guns can be, you should expect 1/2 moa or better @ 100yds from either of these (don't argue that an AR cant shoot like that, its a fact!).

The only reason an AR can keep pace with the bolt gun is because the accuracy is built into the upper, period. A tight fit makes the gun feel better to the shooter, which would boost confidence, which would show up on the target.

AK103K
February 11, 2010, 07:05 AM
Uppers and lowers do NOT have to be tight. It's not milspec to hammer the pins out. Those WHO HAVE SERVED and shot military weapons know this.

Anybody?
Your really hung up on this for some reason. Whats your point?

I've shot military rifles, both rack and match grade, my whole life, including M16's. Not all of them are sloppy and not all "tight" AR's require tools of any kind to get them apart.



A tight fit makes the gun feel better to the shooter, which would boost confidence, which would show up on the target.
Thank you. Basically my point all along.

Double Naught Spy
February 11, 2010, 09:54 AM
Uppers and lowers do NOT have to be tight. It's not milspec to hammer the pins out. Those WHO HAVE SERVED and shot military weapons know this.

No, they don't have to be tight, but being properly fit without play isn't the issue you are making it out to be. However, since you have stated what is not mil spec, then you won't mind citing the mil spec parameters on what is required, will you?

The Tourist
February 11, 2010, 10:59 AM
I wonder if we're actually talking about two distinct needs.

For example, none of us would like a really loosey-goosey 1911 that prints a 12-inch group. And yet tens of thousands of those pistols went to war.

In our present handguns, some folks need a bushing wrench to strip their pistols.

Two different needs, two differing tolerances.

And there's a good reason. I paid a custom gunsmith several bucks to get a bushing fitted with no slop, but one that could be turned with just my hand. That method of "fit" would bog down an assembly line making combat-ready ordnance, not to mention the stoppage problems caused by filth.