The enhanced upper is monolithic, not a traditional threaded upper, not applicable here
M5E1 Enhanced
M5 Threaded
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AR10 barrel nut problem
- Thread starter ntsqd
- Start date
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M5E1 Enhanced
M5 Threaded
The gas key on the BCG would not align if that was the case, the Aero would use a proprietary BCG
I am with everyone else, the nut is not fully machined, otherwise, there would be a whole host of other issues.
S-One is what the OP has
ntsqd
Well-Known Member
Thank you for what I've bolded! That doesn't seem to be understood by many. I didn't understand it until faced with this and had to think about things. High and low would require different gas tubes and gas keys if they weren't the same. I'm curious about those who say you have to use a large frame gas tube. In the massive range of my experience (3 large frame upper builds, note the heavy sarcasm!) this has yet to be the case. Being notoriously curious I'm wondering what they've run into that makes them say that.
Aha, going looking to see what the APRH308910 nut looks like allowed me to find the nut that I do have, it is the APRH100887C Looking at that image the gas tube grooves are not very deep. I suspect that I'm going to be making one of those grooves deeper. Works with their uppers, which is all that any mfg. can really do because they have no control over what any other mfg. does, but for whatever reason doesn't work with the CMMG upper.
Aero barrel nut and Aero hand-guard, they came together.
So do I unless Aero determines that the nut's machining is wrong and replaces it.
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Two things that I wish were different. A) That I could buy the Aero Enhanced monolithic upper with a hand guard that lacks a rail down the top of it. I really have no need for such a thing and don't like the looks of it (The S-One was as close as I could find). B) I could, and do on small frames, live with a full length top rail if I could get a flat bottomed hand-guard like the SP3Rv3 for a large frame. Best would be a flat bottomed hand-guard with no top rail.
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As can be seen, it just barely doesn't work:
I couldn't get the camera right down coaxial to the clover-leaf hole, this is as close as I could get it:
From the inside, can see three of the four tangs in the clover-leaf hole:
Without the barrel nut it slides in like it is supposed to, and has about equal free motion in all 4 cardinal directions. Can also see that the bends are nowhere near the nut:
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Just learned something else. A Nicholson chain-saw sharpening file is very close to being exactly the right diameter to lay in those grooves without rolling or rocking.
I haven't seen the nut for the atlas before, so unaware of how it looked. With a low-profile gas block on an AR10 the Z bend is necessary. If it's not then a straight tube is fine. With the gas block and tube installed insert the bcg into the upper and put it into battery. If it closes and unlocks without a drag feel, them it's good. Finding the cause (like you have) and knowing how to fix it is usually easy? If the clover has some overspray/slag just enough to cause the nut to feel like it's the problem, it might not be the nut? With the tube end that goes into the key it's slightly larger than the tube as so to seal the gas. Try to install it as straight as you can into the clover and see if it drags/catches any. Or just use a round or half-moon file and remove in the necessary material place on the nut.Thank you for what I've bolded! That doesn't seem to be understood by many. I didn't understand it until faced with this and had to think about things. High and low would require different gas tubes and gas keys if they weren't the same. I'm curious about those who say you have to use a large frame gas tube. In the massive range of my experience (3 large frame upper builds, note the heavy sarcasm!) this has yet to be the case. Being notoriously curious I'm wondering what they've run into that makes them say that.
Aha, going looking to see what the APRH308910 nut looks like allowed me to find the nut that I do have, it is the APRH100887C Looking at that image the gas tube grooves are not very deep. I suspect that I'm going to be making one of those grooves deeper. Works with their uppers, which is all that any mfg. can really do because they have no control over what any other mfg. does, but for whatever reason doesn't work with the CMMG upper.
Aero barrel nut and Aero hand-guard, they came together.
So do I unless Aero determines that the nut's machining is wrong and replaces it.
----
Two things that I wish were different. A) That I could buy the Aero Enhanced monolithic upper with a hand guard that lacks a rail down the top of it. I really have no need for such a thing and don't like the looks of it (The S-One was as close as I could find). B) I could, and do on small frames, live with a full length top rail if I could get a flat bottomed hand-guard like the SP3Rv3 for a large frame. Best would be a flat bottomed hand-guard with no top rail.
----
As can be seen, it just barely doesn't work:
View attachment 556684
I couldn't get the camera right down coaxial to the clover-leaf hole, this is as close as I could get it:
View attachment 556685
From the inside, can see three of the four tangs in the clover-leaf hole:
View attachment 556686
Without the barrel nut it slides in like it is supposed to, and has about equal free motion in all 4 cardinal directions. Can also see that the bends are nowhere near the nut:
View attachment 556687
----
Just learned something else. A Nicholson chain-saw sharpening file is very close to being exactly the right diameter to lay in those grooves without rolling or rocking.
BTW, great pics! Makes info a whole lot better!
ntsqd
Well-Known Member
Follow up on this, Joshua at Aero is sending me a new barrel nut. Will dredge this up one last time when I get it and have been able to try it out.
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ntsqd
Well-Known Member
Nothing really worth noting. I have the replacement barrel nut in hand, but I've not had time to look into it.
Please report when you can
ntsqd
Well-Known Member
Finally had some time to try the second barrel nut. No go. It too doesn't allow the gas tube to align correctly in the clover-leaf hole.
Recall my previous comment about how a chainsaw sharpening file is *just* the right size? The nut that works has one of it's grooves deepened slightly using one of these files.
Recall my previous comment about how a chainsaw sharpening file is *just* the right size? The nut that works has one of it's grooves deepened slightly using one of these files.
I guess if it works and your happy, so be it. I (you too) would have really liked to know the exact root of the problem, but oh well. Stay safe and have fun.
ntsqd
Well-Known Member
I'm pretty sure that the tolerances of the clover-leaf hole are tighter in the CMMG upper than they are in Aero's uppers. Not by a lot because it didn't take much filing to get it to go. The groove in the Aero barrel nut is designed to work with their parts. Since there is not a true std. like with the small frames this is exactly what I would do were I in Aero's or anyone else's shoes. My parts will work with my parts, but use someone else's part(s) and I'm not going to guarantee anything.
There is a standard for the AR15. It follows the M16 and M4. If this is a large frame, all bets are off. I cant tell you how many fitment issues I had when I built my first AR10. Ouch! No matter. My guess is that since you stated the CMMG upper did fit with very minimal filing, it's possible the issue is a very small bit of excess metal in the mold design or machining program. If your upper is Cerakoted, then they probably didn't allow enough clearance allowing for the thicker coating. I have seen this happen on other parts. Coatings reduce clearences. Make parts fit tighter. An example being bolt carriers. Chromed ones are very picky about this issue. Stay safe and have fun.
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