Ar Upper and Lower thoughts

[zaman]

I just sold a few firearms and am looking for my next project. I am wondering what brand "reasonably priced" Ar upper and lower people recommend or have good sucess with.
Billet seems to be more money than I want to spend.
Just because the manufacturer says mil-spec does that mean all milspec uppers and lowers will fit perfectly together?
Anything I should look for or watch out for?

[dirtmcgirt76239]

yes they will fit if they are ar15 its all standardized, ar10/ar308 have two different lowers, and then a couple variations by different makers in each of the two, so do not go nutz part ordering with asking someone else.

Aero precision is a good place to start.

[Fuel Fire Desire]

Depends on what you mean by “perfectly” together.

I have a very high end billet receiver set on my race gun (as in a +$400 matched set), and it has the same slop as my last budget basement build.

Do they fit together? Yes

Do they “match”? Cosmetically and functionally yes.

Is there still wobble between the two? Sure is.


The lower even has a tension screw to eliminate the slop, but I can’t get the thing to stop backing out and getting loose again, so I just threw in an Accu-wedge to take some of it out.....on a well respected big budget matched set.

[castrotikon]

I recently worked with a Spike's lower on one build that I was pretty happy with and an Aero Precision on another (honestly, I can't tell much difference between the two but they're both pretty reputable and fairly priced). I did a Ballistic Advantage upper on the one I had an Aero lower on and again, was happy with it. I picked it up for a pretty good price over Black Friday when they threw in the upper receiver for free if you bought a barrel.

One thing I would caution since I just ran into it: not all lower parts kits are built the same...even if they claim to be mil spec. I usually try to get reputable parts (i.e. a LPK from Spike's or something) and since I wanted to just build something dirt cheap for my pistol, I went with some no name brand that came with a grip and everything. It was a complete pain: the trigger couldn't be installed without removing the safety and the j spring in the hammer was so stiff I had to pound on the hammer pin for a good 5-10 minutes before it finally went through. Grip couldn't be tightened with a screwdriver, all the various springs were just tossed in a bag. Had I known all of that, I would've just spent the extra $20-30 and bought a better kit.

[DrScaryGuy]

there are tolerances involved in everything. If you buy from different manufacturers, they might be on opposite ends of the tolerance ratings and not work very well together. Is that likely to happen? no, but it has been known to happen. I've got one upper from a pretty reputable company, but they must have very tight tolerances, because i could not make their lower fit on ... 10 or so lowers. I bought it used though, so I had to do a little garage work on it to make it fit. If I had bought the same brand upper and lower new, I would have been able to get better support.

Anyway, if you know mostly what you want, you can run it by mgo member Danco411. He's some kind of dealer/smith who has been known to order parts for people, do custom cerakote, and either build it for people or show them how to build at his own shop. I don't think he's in your area though, but it might be nice to plan a drive for an afternoon project
This seems to be his info...

Arclight Precision, LLC
Fenton, MI
Firearm Refinishing, Cerakote, Custom Firearms and Ammunition, Suppressor Sales
Class 07 FFL - 02 SOT

[BillR]

I have a few spikes uppers and lowers and no problems at all, very nice . I have one BCM upper and its on par with Spikes for fit and finnish but has a tighter inner diameter where the barrel fits, this is advertised to provide for better accuracy. I just returned a Aero Precision upper due to the charging handle catch hole being very shallow and not much edge for the charging handle to catch on, this was a heads up for me to start checking this area on future purchases for any brand.

Dont listen to the people who say they are all the same, there may be only a few places that create the forgings but the forgings have to be milled to proper specs. Some are better than others for this process.

[hunterspirit]

Also note that resellers will buy out a blemished lot. Usually the blem is they fit sloppy

Lots of Blem Spikes parts out there.

[JohnS624]

AR upper/lower fit is overrated.

[hunterspirit]

I don't share that opinion

[Fuel Fire Desire]

AR upper/lower fit is overrated.

It doesn't affect function at all.....but man is it annoying to have wobble on a $1800 build after you buy a top of the line matched receiver set. Especially since the AR that has had the least wobble in any that I've owned was a budget $650 build using an MGO lower and a bargain basement upper.