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Discussion Starter #1
Having read many experts saying truing the upper receiver is a very good move, I ordered a kit that should be here in a few days. It has a machined insert, 220 grinding compound, and a flexible shaft to insert in a drill for power. I also have two DPMS Slick Side Uppers in route. The DPMS Slick Side upper is much thicker and will be more stable aiding dependable repeatable accuracy. The ARP 16" Scout barrels are here and I look forward to the seeing the accuracy they are so well known for.
 

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They are a handy tool to have just for reassurance and of course you can never have to many tools. The biggest benefit of trueing the face is eliminating uneven loading of the bolt to the extension and possibly breaking your bolt. Some receivers won't need this but now you will know for sure, hope yours are square to begin with.
 

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Discussion Starter #4
Have heard only good things about them.
 

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I just ordered one myself. I replaced the free float tube and barrel nut on my AR pistol. But when I went to sight in the backup iron sights and ran out of adjustment on the rear sight. After doing some research a lot of people say that squaring up the upper should fix the problem.
 

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Discussion Starter #6
three...........yes, several reviews mentioned squaring the upper made all the difference.
 

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Some receivers really need it, some don't even when they are from the same manufacturer. I take off as little as possible, just until it makes contact all the way around, sometimes that isn't all the way through the finish. One of the advantages and gets rarely mentioned is aligning the barrel nut, if it doesn't line up after being properly torqued, just take a VERY light cut and try it again.
 

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three...........yes, several reviews mentioned squaring the upper made all the difference.
That may well be true.

I have done at least a dozen Aero uppers in the last year and all they ever needed was to clear off the coating with the trueing rod and it has never taken more than a minute to verify that the receiver's were true. I still do them all anyway just to check.

The Aero M4E1 upper is an entirely different animal. The Wheeler trueing tool will not fit inside the upper. The M4E1 forging allows the barrel nut to secure the barrel to upper and that's it. The upper is forged in such a way that the hand guard is secured to the upper receiver and not the barrel nut. The extra material in the forging renders the Wheeler tool useless.

That said, I have built four of the M4E1's. Three in 5.56 and one in 6.8 and have not experienced any fitment or performance issues.

It may sound like I am a Aero fan & that is true. I have built on other uppers that needed grinding to get the upper true & I won't name any names. The Aero's have always been good to me.

If you bought an Aero M4E1 upper, the trueing tool will probably not help you.

That's six cents for me today & I am sure that if I have misspoken, I will be corrected.

Ole Silver
 

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I got the truing bar from Brownells to do my Aero upper. It was slightly oversize, enough so that it would only go 1/3 of the way into the receiver, so my local machine shop skinned the bar just enough to let it fit without restraint. Took just 10 minutes to get everything set up and to true the receiver. I put it on an Aero Gen 2 lower and the lock up is perfect. That rig is waiting for my 7mm Valkyrie barrel. I have a feeling its going to be a real shooter.
 

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I got the truing bar from Brownells to do my Aero upper. It was slightly oversize, enough so that it would only go 1/3 of the way into the receiver, so my local machine shop skinned the bar just enough to let it fit without restraint. Took just 10 minutes to get everything set up and to true the receiver. I put it on an Aero Gen 2 lower and the lock up is perfect. That rig is waiting for my 7mm Valkyrie barrel. I have a feeling its going to be a real shooter.
Understood, but the bar would need to go on a milling machine to pare it down to fit the M4E1 receiver. It's not even close.
 

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I got the truing bar from Brownells to do my Aero upper. It was slightly oversize, enough so that it would only go 1/3 of the way into the receiver, so my local machine shop skinned the bar just enough to let it fit without restraint. Took just 10 minutes to get everything set up and to true the receiver. I put it on an Aero Gen 2 lower and the lock up is perfect. That rig is waiting for my 7mm Valkyrie barrel. I have a feeling its going to be a real shooter.
Rifter,

Is your Aero upper a M4E1?

Ole Silver
 

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Not sure how these cutting tools work but IMO how do we true a receiver w/o an starting zero on the main axis?
For this I would think one needs a lathe and indicate the work with precision tools.
Fitting a cutter to the receiver might be better than nothing but how does one know it is trued if one cannot measure it?
I see huge tolerances in receivers. some I tossed away for that reason.
Or maybe I am not understanding the tool and process so please explain.
with all that said a close enough might be enough I just want to know what truing means for some people.
Thanks.
 

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It's actually a crude method of squaring the receiver face to the axis of the bolt. The lapping tool rides tightly in the bore of the receiver and simply squares the face of the receiver to the bore of the bolt.
 

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Discussion Starter #15
FirstMarine-----Brownells has a short video explaining the squaring/trueing process that is pretty informative.
 

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The M4E1 is an upper/integral handguard combination that takes an internal barrel nut. When put together it basically makes the equivalent of a monolithic upper. There currently is no way to lap the receiver. No commercially available means anyway.
http://aeroprecisionusa.com/ar15-m4e1-enhanced-upper-receiver-fde.html
I wasn't aware that it was a one piece setup. Since the benefits of truing are so well known, seems kind of pointless to build a receiver that you can't true.
 

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I wasn't aware that it was a one piece setup. Since the benefits of truing are so well known, seems kind of pointless to build a receiver that you can't true.
It just needs someone with a lathe to turn down the cutting surface of the lapping tool so that it would fit inside without hitting the threads.
 

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Not sure how these cutting tools work but IMO how do we true a receiver w/o an starting zero on the main axis?
For this I would think one needs a lathe and indicate the work with precision tools.
Fitting a cutter to the receiver might be better than nothing but how does one know it is trued if one cannot measure it?
I see huge tolerances in receivers. some I tossed away for that reason.
Or maybe I am not understanding the tool and process so please explain.
with all that said a close enough might be enough I just want to know what truing means for some people.
Thanks.
The tool slides down the bore of the receiver. The tool spins. The front edge of the receiver being squared is square to the tool and bore. The tools work as thousands can attest.
I have used a lathe to true the receivers for over 20 years but the same thing can be done with these simple tools as long as the tool is square to itself.
Mega receivers have a tighter bore. As long as the barrel extension is tight to the bore(no wobble) it is held by the diameter of the extension and receiver there is no need to square the front of the receiver.
If the extension has a sloppy fit to the bore the barrel will be aligned by the flange of the extension and the front of the receiver which if unsquare will point the barrel off to one side,up or down.
 

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It just needs someone with a lathe to turn down the cutting surface of the lapping tool so that it would fit inside without hitting the threads.
Barrel extension is 1.175 in diameter where it meets the receiver. My lapping tool is 1.370 in diameter on the working end of the tool. If one were to reduce the diameter of the working end of the tool to 1.175 on a milling machine, the lapping tool would clear the threads and work fine. It would be more of a PIA to clean up the receiver afterwards though.

My experience with Aero receivers machining quality has shown that the receivers are trued during the machining process. I have never had to remove more than the coating to prove that they are true.

My level of confidence is such that I am not going to pay a machinist to turn down my lapping tool unless I suspect a problem.

Ole Silver
 

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Barrel extension is 1.175 in diameter where it meets the receiver. My lapping tool is 1.370 in diameter on the working end of the tool. If one were to reduce the diameter of the working end of the tool to 1.175 on a milling machine, the lapping tool would clear the threads and work fine. It would be more of a PIA to clean up the receiver afterwards though.

My experience with Aero receivers machining quality has shown that the receivers are trued during the machining process. I have never had to remove more than the coating to prove that they are true.

My level of confidence is such that I am not going to pay a machinist to turn down my lapping tool unless I suspect a problem.

Ole Silver
If I pay anyone to turn my tool it won't be a machinist. Non Chlorinated Brake Parts cleaner is great for cleaning out those receivers after lapping. It is the same ingredients as Gunscrubber but at a fraction of the cost. I buy the generic store brands sometimes as low as $2 per can.
 
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