Matching upper and lower receivers.

[porterdavid98]

Virtually every AR15 I have ever touched has that annoying looseness between the lower and upper. Found a great article addressing this issue and the explanation put the problem as plus mill spec and minus mill spec. That is if the upper leans more to one side of the acceptable tolerance and the matching lower leans in the opposite direction for tolerance you can end up with sloppy fit (not tight).

Would that suggest we should buy matched upper and lowers as a combination only?


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[davsel]

$2 Accu-wedge

Works every time

[00tec]

I have one of those rubber plugs in one of mine. My new build has a tension screw that adjusts the slop.

[hatidua]

I'm apparently not annoyed easily enough

[Circuits]

Would that suggest we should buy matched upper and lowers as a combination only?

Even if you buy them as a matched set, and they somehow fit airtight and slopless, they're going to loosen up over time as you shoot them.

I personally don't like the "accuwedge" or tension screw solutions because they put and keep the halves under tension, which will increase wear on the takedown pin and the hole in the post, but it will make them feel tighter if that's what's important to you.

[ray1970]

I'm apparently not annoyed easily enough

Ditto. Nature of the beast.

[SouthPaw]

Never has bothered me enough to address it. My precious (Seekins SBR) has the tension screw and I leave it back out. As Ray said, it's nature of the beast.

[Brian]

Get a suppressor and shoot a lot. You'll have so much crud backed up into your gun that it starts oozing out between upper and lower, reducing the wobble.

... only partially kidding.

[izzy]

This used to bug me but I've long since stopped caring.

[Dave_L]

Get a suppressor and shoot a lot. You'll have so much crud backed up into your gun that it starts oozing out between upper and lower, reducing the wobble.

... only partially kidding.

LOL! My hand was black in between my thumb and index finger after a range day a few weeks back.