I know you can get matched sets when you pay up for the forged receivers, but is there a basic receiver/upper that provides a tight lockup without shims?   I've never had luck with two different manufacturers, and don't know which manufacturer will provide a tight lockup when you buy the upper and lower seperately.  any ideas.

My Anderson uppers (3, all no-FA and no-dust cover) all lock up tight with several different Anderson lowers and PSA lowers.

But you can always use an accu-wedge if it means that much to you...

It's mostly luck of the draw. Of all mine the best, by far, is my DPMS. Hold it up to a bright light and see nothing yet pins pop out easily. Means nothing though.

I'll second SOLGW. Their receiver fit is extremely tight.

anything zev/mega. they make the receivers for SOLGW, jse, expo, capital armory, and probably a couple others im missing

'xactly ^^^

Mil spec is mil spec.  Tolerance stacking produces some that fit tight, some loose, within the same brand, even so called top-tier companies.

Just the luck of the draw.  Accu-wedge if you must.  No guarantee paying more will make any difference.

Another option would be to purchase a lower with a tension screw installed.

Of those I've personally owned (and excluding billet since you said forged), from Best to Worst:

1) LWRCi (heads and shoulders above the rest)
2) BCM (2016-ish Manufacture)
3) KAC
4) Believe it or not, Colt (circa 2015 manufacture)
5) Wilson Combat - I've seen (but not owned) some other Wilsons that are better, and I spoke with them about mine and they said they had redone their processes to improve.  PLUS, they have the rubber piece that pushes up on upper receiver that prevents any looseness.
6) LMT.  For LMT, I have some that have gaps that you can basically slip paper clips through, and others that are so unfinished that it takes some significant force to be able to get the pins in.


This question makes me feel young again.  I remember back in the day when people used to say "looseness/lack of fit doesn't affect accuracy", which of course is rubbish.  Everything affects accuracy.  Will it be noticed with mil ball ammo?  Maybe not (and depending on what "type" of shooting you're doing (running and gunning/longer range stuff), but it still affects it.

Robinson Armament XCR bro.

eta: sorry, just noticed that this is in the AR-15 build subforum.

But still, if more people bought XCRs we wouldn't have questions like this.

(I like them)

My aero and seekins lower both have a tension screw

My aero upper and lower fit together tight with no wobble at all and I never touched the tension screw, but it's there if you need it. As was mentioned slop between the recievers means nothing, but it does add to the overall quality feel when they are tight.
Edited because I can't text for shit

I'm no expert, but just a few hours ago I used the tension screw in my Aero lower to eliminated some rattle with a PSA upper. Worked like a charm, though if you tighten it any past "just touching" the takedown pin gets a LOT harder to push.