Receiver set question need help

[Nodayhunter]

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.

 

[Dr. Davy Jones]

I would think so. IMO no manufacturer would want to set up two different tolerances for the same product if they didn’t have to.
In my experience, even the same company can make some upper and lowers that are super tight and others that have a little play. My BCM has a little play but I know others have a BCM that’s super tight.
If it really bothers you, use an accuwedge or even better-a layer of electrical tape. Cheap and super effective for me.

 

[Bigjake83]

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's nothing wrong with liking a tight fit , And usually buying a QUALITY upper and lower separately from the same company generally will produce a nice fitting setup, but! If you start mix and matching the cheaper side of things like Areo precision and Anderson you generally are more apt to run into slop. Also Don't be fooled by buying a matched set as some companies rely on their fit by using a form of tensioning bolt under the rear takedown. So my advice to you is to specifically find out what you're looking to buy and then just ask one of us here because chances are one or two of us probably have what you're already thinking about and can tell you how it fits.

 

[NineHotel]

There was a time when there was quite a bit of variance in fit. That time seems to have past, even with some of the jankier brands still producing upper and lower receivers. QC has improved.

Personally I'd not get too wrapped up in fit as long as you are buying a decent brand or a pop-up brand where you know who made the receivers then put the brand name on it.

 

[Nodayhunter]

I am specifically looking at the 2a armament balios lite gen 2 receiver set if that helps. The reason for this is that I am mainly a coyote hunter at heart. I built an ar15 using the above matched receiver set that I am in love with. I don't know if I just got lucky or what but its 1/2 moa gun all day long with factory ammunition. With my state legalizing the use of thermal optics, I want to build an exact replica of what I already have that way I can have a dedicated day and night setup. But I cannot find a matched receiver set only upper and lowers sold separately.

 

[NineHotel]

" I am specifically looking at the 2a armament balios lite gen 2 receiver set " - well if the number of adjectives is any indication, this must be one hellova awesome set of aluminum chunks. Never chased the hype of custom AR receiver sets myself, considering the lower and lower fit HAS NOTHING TO DO with the accuracy of an AR. Good luck finding what you are looking for.

 

[Bigjake83]

Considering the lower and lower fit HAS NOTHING TO DO with the accuracy of an AR. Good luck finding what you are looking for.

Sorry guy but that's just not true... There's a whole host of issues a loose fitting lower can either exacerbate or induce, IE carrier tilt, cycle, hammer strike, bolt bounce.... So on and so forth.

Some people are hands-on learners so I'll put it to you this way... Take a bolt action rifle and shoot a group, then take that same bolt action rifle, loosen the action screws so it has about Just enough slop when you shake it you can hear it rattle around. Now shoot another group.. we'll wait......

Don't take this the wrong way it's nothing personal but chances are you're probably not a good enough shot with the Semi-Auto to clearly see the difference a tight fitting precision AR makes vs a Rattle Box, thus the reason why you have that opinion.

 

[bfoosh006]

" I am specifically looking at the 2a armament balios lite gen 2 receiver set " - well if the number of adjectives is any indication, this must be one hellova awesome set of aluminum chunks. Never chased the hype of custom AR receiver sets myself, considering the lower and lower fit HAS NOTHING TO DO with the accuracy of an AR. Good luck finding what you are looking for.

Could you explain why you feel, a tight upper to lower fit has noting to do with an AR's accuracy ?

 

[vinniedelpino]

Could you explain why you feel, a tight upper to lower fit has noting to do with an AR's accuracy ?

Any experiments to prove/ disprove this? Obviously you don’t want any play between receivers. But I don’t think a matched set Offers noticeable improvement over a set screw lower or accuwedge.

move neverdone any controlled experiments though. And I’ve never had a gas gun that shot better than maybe .6 Moa.

 

[NineHotel]

Let me know when you get it built and where you are - maybe we can put up my adjective absent builds up against the esoteric ones.

 

[Bigjake83]

Any experiments to prove/ disprove this? Obviously you don’t want any play between receivers. But I don’t think a matched set Offers noticeable improvement over a set screw lower or accuwedge.

move neverdone any controlled experiments though. And I’ve never had a gas gun that shot better than maybe .6 Moa.

The accuwedge and the Tension screw both work the same way by causing each receiver to push away from another, this fix is problematic by design. They both induces stress and cause receiver flex.
I've seen the accuwedge and tension screws both cause issues because people use them on receivers that honestly dont need them, And yes it will cause unexplained flyers and cause your groups to open up.

Just remember when trying to fit the upper and lower together you need to do it in a way that does not induce any receiver stress. The fitted JP take down pins are a nice option.

One of the many positive attributes to the Seekins SP-10 is the receiver fit, the fit and tolerances are exceptional. All AR's over time will loosen up just from normal use but I have been very pleased with how its maintained its tolerances.

 

[Jgault]

I am specifically looking at the 2a armament balios lite gen 2 receiver set if that helps. The reason for this is that I am mainly a coyote hunter at heart. I built an ar15 using the above matched receiver set that I am in love with. I don't know if I just got lucky or what but its 1/2 moa gun all day long with factory ammunition. With my state legalizing the use of thermal optics, I want to build an exact replica of what I already have that way I can have a dedicated day and night setup. But I cannot find a matched receiver set only upper and lowers sold separately.

2a is my favorite parts maker. I have a xanthos 308 I built using their upper, lower, and rail. Tightest fitting upper and lower I’ve seen, it has a tension screw but didn’t need it at all, all three pieces fit together like a glove. One thing they are built to tight tolerances, the barrel was very snug to get into place.

 

[702lineman]

I just finished up a pri mk12 mod 0 upper and built a clone lower from a 80% build. I am having this problem with this build. My seekins ar is tight as can be. If you are starting from scratch the seekins are great.

My problem is actually almost all in the front pivot pin, mostly on the pri upper. The jp takedown pins are probably my fix, but I have seen people use shims on the side of the uppers lugs to take up slop, and even seen people bed the upper to lower fit.

I'll try to follow up when I get the oversized pins in and fit up. Problem is the jp pins are out of stock everywhere.

 

[Powder_Burns]

" I am specifically looking at the 2a armament balios lite gen 2 receiver set " - well if the number of adjectives is any indication, this must be one hellova awesome set of aluminum chunks. Never chased the hype of custom AR receiver sets myself, considering the lower and lower fit HAS NOTHING TO DO with the accuracy of an AR. Good luck finding what you are looking for.

A good barrel and trigger will make a huge difference over a parts gun slapped together for the lowest price, but there is something to be said for top shooters’ choices for match grade service rifle competition.
I recommend Pat Sweeney’s books on ar-15 gunsmithing, there are a few chapters on accurizing and tight receiver and barrel fit is stressed a lot.

 

[hino895]

I’ve Cerakoted at least 100 upper and lower sets over the past 7 years.
Even the famed mega arms which was tighter than a mouses ear had slop and loose after coming out of blast cabinet.
Wilson combat is one of the worst their anodizing is really nice but very thick and as they wear in they too become loose.
When they wear in just dab a little paint on the pivot points and it’ll be like new again.