AR-15 Upper/Lower Receiver Rattle

[JohnZ]

Hey guys, I just picked up my first ar last week and when I was fondling it at home, I noticed the rattle between the upper and lower halves. I found it annoying and did some searching on possilbe fixes. The easiest one I found was to use a #7 o-ring and slip it around the two blocks where the cross pins, which hold the upper and lower halves, go through.(From a thread on AR-15.com) This worked great for me, no more annoying rattle and the solution cost me about 20 cents. I know this doesn't improve accuracy, but it takes care of that rattle!

[Track Rat]

My AR rattles a little also when I shoot it. I can hear it somewhere near the buffer tube area. Annoying as all hell so I feel your pain.

But I think for the most part there's going to be rattles here and there. My Colt 6920 does the same thing along with my built AR.

[Jason25]

Hey guys, I just picked up my first ar last week and when I was fondling it at home, I noticed the rattle between the upper and lower halves. I found it annoying and did some searching on possilbe fixes. The easiest one I found was to use a #7 o-ring and slip it around the two blocks where the cross pins, which hold the upper and lower halves, go through.(From a thread on AR-15.com) This worked great for me, no more annoying rattle and the solution cost me about 20 cents. I know this doesn't improve accuracy, but it takes care of that rattle!

Accu wedge

[JohnZ]

Like I said, the o-ring was the most cost efficient fix. Fixed the problem. Just wanted to share with everyone else.

[nitroxdiver]

Yep, normal. Some have more play than others. Most leave it be. Your solution is a good one as it doesn't add anything "into" the lower that can induce potential malfunctions such as the accuwedge or a foam earplug under the rear takedown pin. There is actually a max allowable spec for the amount of play between the upper and lower, measured with a feeler gauge. Don't have it handy right now but Ive seen it written before in a PDF of an inspection manual.


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[sffred]

Usually rattle happens with "non-matched" ar uppers and lowers. One of my noveske's that was built by them has no rattle, the other noveske upper, and noveske lower has a slight rattle. I believe if its completely built from the manufacturer it won't rattle, if you build it, it might rattle depending on parts. Find where's the most play at. If it rattles in the rear- accu wedge. If it rattles in the front oring method

[P.Charm]

i like the rattle on my AR.

[ScottsBad]

The accu-wedge is the way to go, it is the best way to get the rattle out. I've not heard of the wedge causing issues.

As for loose vs. tight fit. It doesn't bother me with an accu-wedge in. And I've not been able to detect loss of accuracy if the upper and lower are slightly loose.

A few months ago I bought another Noveske upper that fits so tight with a new Noveske Gen 2 lower unmatched that I have to use a tool to get the pins out.

However, most un-matched upper and lower combinations I've messed with fit a little loose. BCM upper to BCM (unmatched) lower slightly loose. LMT lower to BCM upper a little loose. Noveske Gen 2 chainsaw to old Noveske upper slightly loose. Noveske Gen 1 lower to Riflegear upper slightly loose. ETC.

The Mega upper and lower (unmatched, and un-built) fit slightly loose too, but the Mega lower has a tightening screw built in.

Would I like all my rifles to fit tight, yeah, but I don't really notice it unless I'm being obsessive.

Maybe others could tell me if they experienced loss of accuracy. I guess if you are shooting target competition it could make a difference.

[Bonedeval]

Mine doesnt rattle at all. Even when i swap uppers. That would annoy the hell out of me.

[l3asturd]

BCM matched uppers and lowers rattle. They are exact on their milspec measurements. Some of the mfgs purposely offset the takedown and pivot holes to get a tighter fit. I like it tight myself, like most guys. But I also like easily removing the pins. It's a fine line.

[thegamettt]

Hey that rattle is probably the buffer. The ones with powder make no noise. I have one that has nuts in it or something and rattles all the time. Take the buffer out and shake it.

[akoba]

I have one that has nuts in it or something and rattles all the time. Take the buffer out and shake it.

Maybe, somebody put a tactical snack inside the buffer tube? lol

[JohnZ]

There is no more rattle, the O-Ring completely took care of the issue. No reason to get an accuwedge, costs 30x as much as the O-Ring fix

[tomd1584]

Or you can just shoot it more and not worry about silly little things like rattle, which is completely normal.

[Mini14]

Glad to hear a little rattle is the norm. Just mated my PSA upper to Mega lower and there is a slight rattle...bugged me at first but I can try messing with the tension screw I guess.