Receiver set question need help

[john white]

[m16]

They should all be machined the same.

That doesn’t mean they are.

It’s really the luck of the draw, you might get an upper and a lower that fit perfectly, you might get a set that are loose right from the start.

You see people doing things like putting o-rings around the lugs on the upper receiver, or putting a bead of silicone between the two receivers to eliminate the slop.

There’s also the “accuwedge” and some lower receivers actually have a plastic tipped set screw to put tension on the upper.

Most people don’t give a crap and just shoot their guns.

I happen to be one of those people.

[instaramen]

There's supposed to be a bit of play in the receivers, especially if it's forged and falls within mil spec tolerances. If you want super tight tolerances, you will want to search for milled receivers which can be machined to tighter specs.

[mansysinatra]

Aero M4E1 has a tension screw in the lower if that floats your boat

[naz]

Should be fine

There are some exceptions. For example, LMT uppers have 2 tabs that you will have to file down to get perfect fit with your lower. Obviously if you got a receiver set or complete rifle that would have been done for you

[ar15barrels]

In today’s times certain receiver sets are impossible to touch.

So my question is this, are upper and lower ar15 receiver sets from the SAME (manufacture/model) machined to the exact same tolerances as the ones that are not sold as a set (where you have to purchase the upper and lower receiver separately but are still the same make and model)

Im super picky about a tight fit and want to know.

There is no guarantee that a "matched set" actually has a tight fit or that 2 random receivers picked out of a barrel full don't have a tight fit.

If you want a tight fit, only buy them after checking them in person.
Go to a store with a large inventory and have them keep pulling out different receivers until you find the ones that fit how you want.
I recommend you wait a couple years before you try this stunt.

[Epaphroditus]

So long as there are demanding shooters there will be gunsmiths to make them happy.

It is impossible for millions of mass produced parts to be interchangeable and not have some fitment issues.

Some designs are amenable to absorbing wide tolerances and some aren't.

[Sparrow Dynamics]

Now is not the best time to be picky.
Yes, some "matched sets" are actually matched where the manufacturer picks an upper and a lower that fit well together. BUT, if you just but a lower, and then an upper from the same manufacturer, they should look nice together and also fit very well. If you pick parts from different manufacturers, they will fit fine together, but they may not look right together. I have some of those really mismatched rifles, but they shoot well. As mentioned already, the Aero lowers have a setscrew to take up the slack between the upper and the lower. Or, you could also buy those little soft plastic wedges to get rid of any wiggle you might not like.

[loademup]

I would think upper and lowers from the same manufacturer have a better chance of fitting "perfectly" together. I have a CMMG Mk 9 LE 9mm AR that I bought the upper and lower separately, and they fit perfectly together.

I also have bought a Del Ton upper and I was surprised that it fits perfectly with my Colt M4 Carbine lower.



So whether matched or unmatched sets, a perfect fit between the upper and lower is unknown until you actually put them together.



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[-hanko]

I also have bought a Del Ton upper and I was surprised that it fits perfectly with my Colt M4 Carbine lower.

So whether matched or mismatched sets, a perfect fit between the upper and lower is unknown until you actually put them together.

I'm definitely not surprised. Del Ton has been making AR parts forever.