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Posted: 3/6/2021 8:04:29 PM EDT
[#1]
Both my aero lowers have excessive gap (.104 and .098)
My psa set has .064 with a psa upper and .079 with a 60s vintage colt A1 upper The best fitting set i have is a fulton lower with a bcm upper. I haven't measured yet. But its significantly less than anything else i own. The aeros i run the tension scew to set the receivers, and the psa/colt i run an accuwedge. The fulton/bcm im not going to do any shims on. Its a non-issue in reality. |
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Posted: 3/6/2021 8:43:36 PM EDT
[#2]
Quote HistoryQuoted: Both my aero lowers have excessive gap (.104 and .098) My psa set has .064 with a psa upper and .079 with a 60s vintage colt A1 upper The best fitting set i have is a fulton lower with a bcm upper. I haven't measured yet. But its significantly less than anything else i own. The aeros i run the tension scew to set the receivers, and the psa/colt i run an accuwedge. The fulton/bcm im not going to do any shims on. Its a non-issue in reality. If those numbers are in inches you might want to adjust the numbers. |
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Posted: 3/6/2021 8:56:37 PM EDT
[#3]
Quote HistoryQuoted: Both my aero lowers have excessive gap (.104 and .098) My psa set has .064 with a psa upper and .079 with a 60s vintage colt A1 upper The best fitting set i have is a fulton lower with a bcm upper. I haven't measured yet. But its significantly less than anything else i own. The aeros i run the tension scew to set the receivers, and the psa/colt i run an accuwedge. The fulton/bcm im not going to do any shims on. Its a non-issue in reality. .104"  ?That is crazy |
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Posted: 3/6/2021 9:07:39 PM EDT
[#4]
Quote HistoryQuoted: What are the go to companies for matched sets? I actually just picked up my first set the other day. I went with the ADM UIC builders set. Mainly because they are actually in stock (2 week lead time) but also because the limited reviews I've seen all speak highly of them. I actually just grabbed them and the colt to compare... the colt does have a little bit of slop whit no mag inserted but a full mag inserted removes it. I was able to fit a .004 feeler gauge between the colt receivers loosely and for the ADM set I could fit it but barely and it was very tight. I think my aero set (large frame) measured somewhere around .010 IIRC which is more slop than a full mag will remove. |
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Posted: 3/6/2021 9:57:15 PM EDT
[#5]
I had a RRA years ago that was so tight, I had to put the rifle together in cold temps because it would be too tight to put together when it was warm. All my rifles are pretty good, with my worst fit being a BCM over Noveske, and best fit being a Stag over Aero M4E1. Ar's be like a box of chocolates, ya never know what yer gonna get.
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Posted: 3/6/2021 10:05:00 PM EDT
[#6]
Quote HistoryQuoted: If those numbers are in inches you might want to adjust the numbers. What lol |
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Posted: 3/6/2021 10:06:20 PM EDT
[#7]
Quote HistoryQuoted: .104" ?That is crazy It is man, aero lowers are trash in that aspect. They all run and have good fit otherwise. But I will not buy another. |
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Posted: 3/6/2021 11:44:30 PM EDT
[#8]
Quote HistoryQuoted: What lol If an upper was raised .064 of an inch the carrier would hit the receiver extension. If you were measuring in millimeters then it would convert to around .0025" and would be a reasonable gap. |
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Posted: 3/7/2021 12:34:21 AM EDT
[#9]
Quote HistoryQuoted: It is man, aero lowers are trash in that aspect. .  Attached FileI have several Aero lowers and they fit great with every upper from Colt to LMT to DD to Aero etc |
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Posted: 3/7/2021 5:25:32 AM EDT
[#10]
Quote HistoryQuoted: Also on a side note, Aero's lower parts kit was pretty trash quality All the Aero lpk's (5) in the past few months I've bought all had Schimd parts. Schimd junk? First I've heard. |
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Posted: 3/7/2021 6:08:58 AM EDT
[#11]
Quote HistoryQuoted: All the Aero lpk's (5) in the past few months I've bought all had Schimd parts. Schimd junk? First I've heard. |
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Posted: 3/7/2021 12:19:54 PM EDT
[#12]
This makes me happy I'm not OCD. My ARs are tools...if they're functional, I'm GTG.
I think a lot of people get worked up about boutique brands...of a mil spec design! Seems crazy to me. Reliability, durability,, and level of accuracy commensurate with it's purpose are all I need. I have two styles... Battle grade with a2 uppers and bone stock everything. I like nitride barrels for durability and dissipator style for the longer sight radius in a 16" gun. All the same so that no matter which one I grab, they function the same. All interchangeable in function and parts. Precision shooter...quality SS 18" barrel with rifle gas, FF handguard, quality 2 stage trigger, upgraded rifle stock and high quality glass. An upper to lower gap, unless it affected function, is a non issue. |
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Posted: 3/10/2021 12:52:51 AM EDT
[#13]
JP Microfit oversized pins will pull the receivers closer together and eliminate some if the gap. They also lessen upper wobble a bit. Strong side tactical usually has them. I think they're about $30. But if you're OCD it's a reasonable cost to tighten things up.
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Posted: 3/11/2021 1:27:06 AM EDT
[#14]
It’s a tool, treat it like one.
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Posted: 3/11/2021 1:43:24 AM EDT
[#15]
That is pretty poor fit for a company with the name “precision” in it, especially considering the PSA I built, you can not see any light through it and the takedown pins push right out by hand so it’s best of both worlds.
LMT has tabs you are supposed to file down to get a tight fitment with the lower, I wonder if Aero has something similar, couldn’t you ever so lightly “sand/polish” the receivers then refinished them once you got a better fitment. The other option is the make the rifle your “workhorse” and beat the shit out of it, have more fun that way anyways. |
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Posted: 3/11/2021 1:46:51 AM EDT
[#16]
Quoted: this is 100% functional and just my OCD This. Every AR has light visible between the receivers like that. The connection is the lugs and pins. The AR design does not allow that interface to be an interference fit and still be interchangeable parts. A different kind of design like a FAL, which uses a camming latch to push the receivers together could have a kind of fit that you desire. Or you can do like some of the match guys and put bedding compound in between the receivers and create a mating set. ETA: just checked 10 ARs, to include Colt and an FN upper with three different brands of lowers two of which are known for tighter fits, and every one has light visible between the receivers. Tight fit/no wobble generally comes from the rear of the rear upper lug having an interference fit with the lower receiver. Receivers that have a loose fit and a "tension screw" work by pushing the upper away from the lower and exacerbate the gap that seems to concern the OP. Accuwedge does the same. Family member has an Aero lower, out of 3 or 4 aero uppers I had sitting around one was a perfect fit with no wobble and just a little tension on the takedown pin, a few uppers I tried would not close so at least with that lower I wouldn't say they tend toward loose fit. I'm not sure I believe anyone has an AR upper/lower combination with more than .100 inches gap between the receivers. |
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Posted: 3/11/2021 10:27:02 AM EDT
[#17]
This thread is really amusing. I cannot believe anyone obsesses over the gap between uppers and lowers, let alone MEASURING the gap. This is fun.
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Posted: 3/11/2021 11:58:04 AM EDT
[#18]
Quote HistoryQuoted: Guys with OCD should not purchase AR's. ETA: now a lot of wobble/movement between upper/lower will set off my OCD on "new" builds |
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Posted: 3/13/2021 11:43:19 PM EDT
[#19]
I buy something give a quick once over then throw it in the safe until I shoot it. I wouldn’t even take notice of that.
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Posted: 3/14/2021 12:35:29 AM EDT
[#20]
This is one of those things that an AR owner can go YEARS without noticing and once you notice it you can't un-see it. It is very similar to the raised portion on the left side of uppers and lowers not lining up - the raised portion where the magazine release is. If you had never noticed an AR where these did not line up you may never notice that some uppers and lowers don't fit together perfectly. See it once and you will notice it from then on out.
All that said, most if not all AR's will function just fine regardless of daylight being seen between upper and lower. It does not seem to affect function at all. |
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Posted: 3/14/2021 1:31:23 AM EDT
[#21]
Quoted: Recently went with Aero precision for a new build, upper and lower are both M4E1. The upper came complete but I have noticed a pretty big gap between the upper & various lowers (all m4e1) and also a pretty good amount of play/rattle. I'm aware of the set screw in the M4E1's that take out the slop but they also make the takedown pins near impossible to remove without a tool. The loose feeling really isn't as big of a peeve as is the gap between the receivers. I've already contacted Aero and been told this is normal but I would like some other opinions from you guys. I understand some space is common but I was hoping for a tighter fit from all the Aero hype especially when comparing to some other cheaper builds i've used including psa/adams which all had pretty tight tolerances with barely any rattle/wiggle. Even if this is 100% functional and just my OCD I'm curious would you guys consider this acceptable/normal for yourselfs. Thanks https://i.imgur.com/zVyUccm.jpg https://i.imgur.com/gz2zGhg.jpg Pics - https://imgur.com/a/EfsP9QY I understand that there's a a gap between upper and lower. But Aero incorporates a tension screw on the lower to adjust away any wobble between the upper and lower. My M4E1 upper-lower sets all have a little bit of play. Not an excessive amount, but they all have a little. But that play is easily removed with the adjustment screw. Have you tried utilizing yours? |
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Posted: 3/14/2021 8:58:30 AM EDT
[#22]
I wouldn’t worry about the play. I have all Aero except for my Smith. No big deal, it’s a tool for defense. What does irritate me is needing a tool to get the takedown pin out. I do not have that problem with my Smith. Have you found a solution to that?
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Posted: 3/15/2021 3:39:32 AM EDT
[#23]
Quote HistoryQuoted: Guys with OCD should not purchase AR's. At the end of the day....It is and always will be....a Military grade weapon built along those specs... Some manufacturers are better then others...but no AR manufacturer would throw that on the QC scrap pile. The true mark of a quality AR is how reliable and how accurate....nothing more. If you're looking for asthetics....start buying $5000 over/under shotguns. |
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Posted: 3/15/2021 4:12:19 AM EDT
[#24]
Quote HistoryQuoted: It would bother me, but it's also Aero. I buy from brands that consistently put out products with higher tolerances and fit/finish. Sure wish I bought more mega sets when I had the chance. |
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Posted: 4/15/2021 9:17:45 PM EDT
[#25]
I guess I’m just fortunate that when I was in my first M4 had noticeable wiggle between receivers. Has never bothered me seeing one after that.
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Posted: 4/17/2021 1:34:55 PM EDT
[#26]
Isn't there an adjustment/tension screw back there? You could loosen it to possibly minimize the gap, but it might allow for more movement. I dont know if any of my Aero guns have a gap. Im too happy with the end product and its performance to look for things like that. I understand the OCD though, so Im not minimizing your concern.
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Posted: 4/17/2021 9:20:44 PM EDT
[#27]
Check out the BROWNELLS ACCU-WEDGE - works great!!!
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Posted: 4/19/2021 9:51:32 PM EDT
[#28]
Quote HistoryQuoted: Guys with OCD should not purchase AR's. That's a bigger gap than you'll usually see, but generally this. |
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Posted: 5/5/2021 10:11:18 AM EDT
[#29]
Interesting thread. I too am an OCD guy and while I get that AR's are "military" type weapons and fit and finish can vary but like 77Bronc, I spent the time and money to make mine fit to my satisfaction but I went about it differently. I've owned a number of AR's over the years but have built all of mine. The closest thing to a factory built AR is an LMT M4 carbine that the lower and upper were both factory built and sure enough, that one has the loosest fit of any AR I currently own.
No, it doesn't effect function in any way but no matter how many people say don't worry about it, it will always bother me Anyway, the solution for me was to stick with receiver "brands" that I found had very consistent milling/finishing. I had good luck with RRA receivers back in the day but then I discovered Mega Machine. I've had over a dozen Mega uppers and lowers from different times/batches and they all matched up perfectly (or damn close to it) both in fit and finish and the later receivers even had the tensioning screw just in case (but never had to use it myself). Mega is now gone and I'm not sure if the Zev made replacements are up to the same standard? Why I find this thread interesting is, I often wondered if Aero would be a suitable replacement? I thought they might be because they come from the same industry as Mega (Aerospace) and those Aerospace guys usually really know how to manufacture aluminum parts but apparently not in the case here? Very disappointing. So yes, an OCD guy can play in the AR world but it will take some extra time and money to find the gear that will satisfy your OCD or you just have to get lucky. |
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Posted: 5/6/2021 11:45:48 AM EDT
[#30]
Does it work? The most important thing to worry about. You can always take a piece of metal from an aluminum can and make a wedge. Just make sure it is in the area of the rear lug. It will tighten up the wobble.
Dan |
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Posted: 5/8/2021 6:42:30 PM EDT
[#31]
Quote HistoryQuoted: Patchouli can be quite relaxing I've heard. Tig...FYI... your in box is full |
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Posted: 5/8/2021 8:41:02 PM EDT
[#32]
My Aero is reliable and meets my needs. It is a tool, after all.
If you want true tolerance nightmares, starting buying expensive 1911's. |
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Posted: 5/11/2021 7:09:33 AM EDT
[#33]
I guess I just don't understand, there are options out there to "fix" the wobble, but the gap is not a problem. If a company really wanted to they could add a lip to the upper forging and mill a corresponding track on either the inside or outside of the lower so they would nest and there would be no gap for light to shine through. If it was an issue someone would do it and tout it as an upgrade (I'm sure someone already has). But...it's not
 As for a 0.104 gap... Decimal placement is kind of a big deal when discussing tolerances. |
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Posted: 5/11/2021 12:34:21 PM EDT
[#34]
OP, have you contacted Aero to find out if this is normal for their uppers fitting on their lowers? They may machine the parts for a little open space to facilitate their tension screw system’s workings.
The gap looks extremely consistent from front to back. And as long as the rifle prints pretty well, this issue is cosmetic. For me, anyway. |
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Posted: 5/11/2021 5:40:30 PM EDT
[#35]
Actually, there is an engineering reason the upper and lower are supposed to have a minimum of 0.002" gap.
Even if you could and did hold the tolerances to zero, you still need a small gap. I'll let you lot figure out why. |
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Posted: 5/11/2021 11:11:04 PM EDT
[#36]
I am looking at some Anderson receivers and they are looking pretty good.
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Posted: 5/11/2021 11:45:35 PM EDT
[#37]
My KAC mod 2 upper sits on an Anderson lower. It’s nice and snug. The Geisselle lower I had planned to put it on had more wobble than I like.
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Posted: 5/24/2021 5:52:13 PM EDT
[#38]
Quote HistoryQuoted: [color=#ff0000][b]Sure wish I bought more mega sets when I had the chance. Quote HistoryQuoted: Quoted: It would bother me, but it's also Aero. I buy from brands that consistently put out products with higher tolerances and fit/finish. [color=#ff0000][b]Sure wish I bought more mega sets when I had the chance. [/color] My MEGA "GTR-3 Ambi-Billet" upper/lower set have virtually no gap and certainly no play... Wife Bought about 7-8 years ago for my birthday (my choosing.) But they fit great just like the Noveske barrel and Centurion FF quad-rail. Hand-pic and if need "fit" a couple AR's together with the tolerances you desire OP and be done with it. You can sell your others for a premium now and worry about 1 thing less. |
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Posted: 5/25/2021 1:00:26 AM EDT
[#39]
I believe the max gap for the Army is .020 with a feeler gauge....they have a specific area of the rifle to measure that gap too. Going off of memory I could be wrong.
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Posted: 5/25/2021 4:36:12 PM EDT
[#40]
Would think guys who build would know by now...
Bottom line: All my AR's now have perfect fit, and I do mean perfect, no gap, perfect line-up, not off in any direction and no over/underlap. How you say? You have to go through a LOT of parts, first you have to find lowers that are cut well and that may take some time, after that you have to play what I call "stripped upper roulette", you basically keep buying stripped uppers until you get one that fits right, sell the others. ALL AR manufacturers have outright lemons from time to time, and now and then they also will put out an absolutely perfect in-spec part, all the rest they make fall somewhere in the middle. Some have vast differences in the height and width and placement of the mag-release area "rib" on the left side and that shit especially bugs me. FWIW call me crazy, but regardless of who does the final machining, I have had better luck with Cerro forgings than with any others. |
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Posted: 5/25/2021 5:09:44 PM EDT
[#41]
I have 2 m4e1 upper/lower sets and they are both equally “sloppy”. Both also have mag wells that have a hard time dropping pmags freely (just a little snug).
For what I paid for them I can’t really complain. If you paid current market pricing I can 100% understand some disappointment. |
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Posted: 5/25/2021 5:31:13 PM EDT
[#42]
You can buy a shoulder bolt at nearly any decent hardware store that you can use to replace the front push pin in the lower receiver. Once you put in the shoulder bolt, and a washer on the other side, you can clamp it down to remove the slop between upper and lower. I have used them on a number of rifles to tighten up any slop between the upper and lower. However, that doesn't do all that much to improve accuracy....it just makes the rifle "feel" more solid.
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