Has anyone addressed the AR wobble?

[454Puma]

I was dry firing my AR and I noticed for the first time there is a wobble( IE not a tight fit between the upper/lower) My question to you all has anyone shimmed the upper/lower to get rid of the wobble and how did you do it! Obviously this will effect accuracy!   Pics would be greatly appreciated if you have. 

[R.W.Dale]

You can buy a product called an "accuwedge" which eliminates and play between the  rear of the upper and lower. But honestly it's been tested extensively and a normal amount of upper/lower play doesn't effect accuracy. However from your description your fitment doesn't sound normal


This said I do use a thin piece of neoprene under the rear pin hole of my 30HRT for reasons of feel alone

[myronman3]

 +1 on the accuwedge.   although i will say, you would think it would make a difference, but in all honesty there is no noticable increase in accuracy that i could see.  and, it makes pushing the pin out alot harder. 

[454Puma]

Thanks for the replies guy's!  I just fine it funny after all those years in service and I never noticed it in the M16?  Of course all I really cared about it went bang when needed!

PS I made a shim and installed it on the left side rear of the lower(on the up slope where the buffer is) and it seems to stop the wobble! Now I'll have to shot it and see if it will last/hold up to the recoil! 

[myronman3]

just make sure your shim doesnt come loose to mess up the action of the rifle. 

[454Puma]

myronman3
 This will be a tempory fix to see if it 1. Will stop the wobble (after being shot) 2. I think do a more permanant fix with JB weld .  I do believe this was the cause of my accuracy problem ! I'll let you know how it goes!

Well I got out and shot some!  Very big improvement in accuracy as you can see. First target is with Fed M193 ball  second is with SEI 69 gr HPBT's  see the nice group of three then the last two is after the slim was removed!  I was very impressed with the Fed M193 as it usually looks like a shotgun pattern it was also very windy today!   Now to do a pernenant fix so it's never a problem again!

[SHOOTALL]

some bed the upper and lower , not sure how though

[stalker1]

Upper to lower fit will have an impact on accuracy. When I build an AR I bed upper to lower. If different uppers will be used on the same lower I use an accuwedge and trim as needed for a tight fit. I have done a lot of testing with many upper/lower combinations and in every test with factory loads and handloads the more loose the fit the the less accurate the rifle. I initially took my cues from the AMU for bedding and later, their use of the accuwedge. There are many things that will affect accuracy with an AR and looseness is one of them. Accuracy is defined by the shooter and what he/she does to improve it or maintain it. What I expect from my AR builds is 0.5 MOA minimum and work from there. The accuwedge is only a couple of bucks and it is very easy to install and remove. But it is not the only answer.
BTW I do shoot an average of 500 - 600 rounds a week for practice(fun) and 200 - 300 more when testing accuracy improvements on my builds. Ranges are between 100 and 600 yards with most between 100 and 300.   

[pruhdlr]

Can someone please explain to me how the upper/lower fit would influance accuracy. Scope on upper,bbl in upper. These are mechanically mated together. All the lower does is slap the back of the bolt with it's falling hammer. Unless your talking a bbl harmonics thing.

How would a ACCUWEDGE stop the wobble if it is in the pivot pin ??

What say ye ?? ---pruhdlr

[SHOOTALL]

If any part of the rifle moves then it would be hard to have the rifle recoil the same each time . Much like if the shooter holds different each shot. Accy is deterined by how close the shooter can control movement shot to shot so the bullets travel out the bbl is effected the same way shot to shot . A lose action in a stock of a bolt gun will do the same .
It puts pressure between the recivers restricting movement.

[jmayton]

The steps to good accuracy that apply to bolt guns do not always apply to AR's.  What gives good accuracy in an AR is the bolt/barrel lockup.  Bedding and tensioning various parts may help that lockup, but it's not about the movement between the upper and lower, it's really about the bolt/barrel.  I could see how excessive movement could be a problem based on the long lock-time of the AR, but I bet a JP speed hammer would take care of that as well. 

Remember, the AR was designed as a battle rifle and therefore everything is designed to be a little "loose."  A buddy of mine built a varmint rig from a Model 1 parts kit and he runs the JP tension pin and swears by it.  But he's shooting for varmints.  I don't see the point on my 16" M4 (plus I can't even get an accuwedge in).  If it's bothering you, then get an accuwedge and try it out.  It might work, it might not.  You could also try the tensioning pin and see what that does. 

I read in an article one time that the upper and lower receivers of the AR are just there "to keep the parts from falling on the ground."  AR's can be extremely accurate, but remember they need a lot of refining to become so (much like bolt actions after WWI) since they were not designed originally for pinpoint accuracy.

[myronman3]

i do not agree that they need alot of refining to become so. go shoot a bushmaster varminter then come back and tell me how much refining you had to do to make it accurate. 

[Oldshooter]

yeabut myron aint the varmiter built any different for accuracy?

[myronman3]

it is still an ar.   i will tell you what, put a scope on my car and i bet it would be pretty accurate, too.   even with iron sites i am doing very well at 300 yards....and my vision is not what it used to be...it starts to blur at that distance.  the gun is far more accurate than i am; and i am no slouch.  
  i know the varminter has a heavier, longer free-floated barrel, and a two stage match trigger that is smoovvvv.   how much the free floating actually helps, i dont know.  what i do know, is i could put bullets through the same hole at 100 yards.  i honestly shot a bee off of my target when it landed on it. 

[SHOOTALL]

The steps to good accuracy that apply to bolt guns do not always apply to AR's.  What gives good accuracy in an AR is the bolt/barrel lockup.  Bedding and tensioning various parts may help that lockup, but it's not about the movement between the upper and lower, it's really about the bolt/barrel.  I could see how excessive movement could be a problem based on the long lock-time of the AR, but I bet a JP speed hammer would take care of that as well. 

Remember, the AR was designed as a battle rifle and therefore everything is designed to be a little "loose."  A buddy of mine built a varmint rig from a Model 1 parts kit and he runs the JP tension pin and swears by it.  But he's shooting for varmints.  I don't see the point on my 16" M4 (plus I can't even get an accuwedge in).  If it's bothering you, then get an accuwedge and try it out.  It might work, it might not.  You could also try the tensioning pin and see what that does. 

I read in an article one time that the upper and lower receivers of the AR are just there "to keep the parts from falling on the ground."  AR's can be extremely accurate, but remember they need a lot of refining to become so (much like bolt actions after WWI) since they were not designed originally for pinpoint accuracy.

Any movement will not aid accy. There are smiths glass bedding the upper to the lower now. I guess we will go thru. the same steps smiths went thru with the 1911 and the same disagreements . That's ok its something to talk about. And i do realize the difference in weapons really but movement in the stock is not good for hitting the target. The amount od movement may depend on shooting style as some support the gun with a couple fingers under the fore arm while others wrench down ont using a sling  along with mant falling somewhere in between .

[SHOOTALL]

it is still an ar.   i will tell you what, put a scope on my car and i bet it would be pretty accurate, too.   even with iron sites i am doing very well at 300 yards....and my vision is not what it used to be...it starts to blur at that distance.  the gun is far more accurate than i am; and i am no slouch.  
  i know the varminter has a heavier, longer free-floated barrel, and a two stage match trigger that is smoovvvv.   how much the free floating actually helps, i dont know.  what i do know, is i could put bullets through the same hole at 100 yards.  i honestly shot a bee off of my target when it landed on it. 

so how much movement does yours have ? I have seen ones you could call sloppy and a few you had to drive the pins in and they had no movement .

[Reverend Recoil]

My AR15 service match rifle has a slightly loose fit between the receivers.  I do not use an Accuwedge.  Last Saturday I shot a 195-8X score at 600 yards.  It could have, would have, should have been a score of 198.  Three of the five points lost were caused not accounting for a change in wind.   I thought the first two 9's were an error in sight alignment.  Maybe next time.

[jmayton]

i do not agree that they need alot of refining to become so. go shoot a bushmaster varminter then come back and tell me how much refining you had to do to make it accurate. 

Let me clarify:  From the military configuration (like my Colt 6920), they need refining to make them superbly accurate. . . like a free floated, long, heavy barrel, and a nice, light, crisp trigger. . . kinda like your Bushy.  My M4 is not capable of that type of accuracy without those changes.

[myronman3]

now i have never scoped my m4 to see what it could do, but i know i would do better than with iron sights.   seeing as how that gun is my fighting gun, there wont be a scope put on it.  i am almost tempted just to see what the outcome would be....

[jmayton]

myronman3, mine will do about moa with my handloads.  I think it could do better with the barrel free floated, so a Troy TRX 7.2 is to be ordered soon.  They're quite accurate for a fighting rifle, but not up to par for a precision varmint rig.