Just that, how critical is receiver truing on a precision type ar15 upper?
Additionally, what's the best method?
Thanks
Additionally, what's the best method?
Thanks
Gunsmithing how critical is trueing a ar15 upper receiver?
- Thread starter Rprecision
- Start date
It would likely be the largest waste of time and money one could spent on a firearm.
Think of hard anodize as the shell on an M&M candy. Look at rifles with 10s of thousands of rounds. Sure it wears a bit, but that sliding action back and forth is what that coating is tailor made for. Impact is where it starts to fail and this is the genius of the AR platform. Nothing really bangs into one another. Nothing AL anyway.
The coating is vital lapping it to get the gun to run just means you bought the wrong parts. None of us would dream of sanding the paint off of our car doors if one hung up. -Treat this the same imo.
C.
Think of hard anodize as the shell on an M&M candy. Look at rifles with 10s of thousands of rounds. Sure it wears a bit, but that sliding action back and forth is what that coating is tailor made for. Impact is where it starts to fail and this is the genius of the AR platform. Nothing really bangs into one another. Nothing AL anyway.
The coating is vital lapping it to get the gun to run just means you bought the wrong parts. None of us would dream of sanding the paint off of our car doors if one hung up. -Treat this the same imo.
C.
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Really good advice from GH41 and Longrifles... The receiver is either made right or it isn't.
I lapped a few. It's a waste of time.
I think OP might be talking about the front end of the receiver threads where the barrel nut threads onto. There isn't any moving parts on that part of the upper.
I have trued the face up on a few just to be sure the barrel extension seats square, not sure if it helps, but probably didn't hurt, and only takes 5 minutes.
I did it pretty basic, used a precision ground 1" bar and put a removable dog in it to drive the receiver through the ejection port. Get the bar running true in the lathe, take a light facing cut, done.
I did it pretty basic, used a precision ground 1" bar and put a removable dog in it to drive the receiver through the ejection port. Get the bar running true in the lathe, take a light facing cut, done.
I was referring to trueing the face.
But it sounds like what I suspected, a waste of time
It is worth doing. I bought a RRA upper and assembled everything to find out that the barrel was so far right that I needed about 20 MOA more of windage to zero it at 100 yards. Lapped it... perfect and now it's trued so yes it is worth it, even on the best upper receivers... sometimes with they coat the gun the coating can be thicker on certain areas and will cause some tolerances to be off
I've done it and couldn't really tell a difference. I don't think it will hurt anything, but I don't think it will make a noticeable difference on accuracy unless the receiver was way off to begin with.
The receiver face lapping tool is, IMO, best used for indexing barrel nuts.
The receiver face lapping tool is, IMO, best used for indexing barrel nuts.
The most critical for the barrel/upper is how much torque is applied to the barrel nut and if oil was applied to the outside of the barrel by the chamber to have a smooth seating of the barrel.
If you torque it to much or not enough it will affect accuracy differently. I in fact had several customers with ARs have me work on ones they bought brand new from a local dealer custom making their own brand complaining about accuracy issue with groupings that would not stay consistent. I inspected the crowns but found they all were not damaged and cut correctly, checked the chambers but they were reamed correctly and rifling look perfect with no damage. Checked the ammo and is shot accurately out of ARs I had in the shop. So I went to take off the barrels to check them and see if somehow they were crooked and once the gas tubes were removed the barrel nuts unscrewed by barely pushing them with one finger!!!
So beyond that truing the upper to the barrel will make it more accurate like it would for any rifle BUT since you are talking about absolute max effective ranges of 500 yards (with custom ammo) it will not make enough of a difference to really help much unless you look down the upper and can actually see the barrel is not lined up, then definitely that would help a lot.
If you torque it to much or not enough it will affect accuracy differently. I in fact had several customers with ARs have me work on ones they bought brand new from a local dealer custom making their own brand complaining about accuracy issue with groupings that would not stay consistent. I inspected the crowns but found they all were not damaged and cut correctly, checked the chambers but they were reamed correctly and rifling look perfect with no damage. Checked the ammo and is shot accurately out of ARs I had in the shop. So I went to take off the barrels to check them and see if somehow they were crooked and once the gas tubes were removed the barrel nuts unscrewed by barely pushing them with one finger!!!
So beyond that truing the upper to the barrel will make it more accurate like it would for any rifle BUT since you are talking about absolute max effective ranges of 500 yards (with custom ammo) it will not make enough of a difference to really help much unless you look down the upper and can actually see the barrel is not lined up, then definitely that would help a lot.
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I face every one of them. It takes so little time and there is no downside. Take any new receiver and place it face down on a surface plate and a square (90 degree) gage against the flattop of the upper. There aren't too many that will be square...it's quite noticeable. After truing the flattop is noticeably parallel to that square. That's not the true test of square to the interior bore, but it's a pretty damnded good indication the face is off. You give a good 90 degree surface to the bore the barrel extension seats into....where is the downside to that? Opening another can of worm here too...do you epoxy/threadlock the extension in the receiver??? Depending on fit of course, but I typically do that also.
I use a PTG receiver facing tool. Chuck it in a drill with lapping compound and just check as I go. I always see some room for improvement. It is just a feel good measure. It doesn't take long. I'll likely never know if it's worth it. I don't thread lock or epoxy the hottest part on the rifle. I could see doing it on a match rifle where your strings of fire might not make heat an issue.
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I have the tool that Brownell's sells and use it to square the face of ever receiver I get. It can only help and can't hurt anything.
i just ordered the PTH face tool and lapping compound. From the research i did, I came to the conclusion it doesnt do much for accuracy (confidence maybe) but it does help center the bore to the upper alowing the sights to be more central vs off too far to one side or the other.
As Chad from Longrifles stated it just removes the anodizing, something you actually don't want to do. The key to making an AR shoot is "float a good barrel." I put that in quotes because it's been stated by a couple of the top AR smiths and I've found it to be true dozens of times.
Look at the bolt lugs. If you blue them and check for surface contact you'll see a lot of layout blue left -no contact, a bolt gun would need trueing or lapping. Shoot the AR-15 a few hundred rounds and then check again -you'll see 100% contact. The gun will wear in, go shoot it.
Look at the bolt lugs. If you blue them and check for surface contact you'll see a lot of layout blue left -no contact, a bolt gun would need trueing or lapping. Shoot the AR-15 a few hundred rounds and then check again -you'll see 100% contact. The gun will wear in, go shoot it.
Not sure if it was your intent, but your post actually makes a better argument for truing/lapping the face then not.
Now, to be fair, I didn't do a great job posing this question on the onset. I am referring to forged, run of the mill receivers. Those with precision billet receivers can ignore this post.
Your suggestion to "float" the barrel strikes me a contrary to the goals of precision. (1) I don't want the barrel to move in the receiver. All of the sighting systems for this platform attach to the receiver. If the barrel moves it will effect POI either shot to shot or session to session, all to me are bad. (2) the discussion of anodizing on the face of the receiver is a mute point to me. If anodizing is the only thing keeping from wearing out that face there are bigger problems. I would suggest that argument is accurate for the interior, but not on these parts.
All bolts wear in eventually, if the barrel is not sitting true to the bore of the receiver this is more of a problem, thus why I tend to believe truing the face is important.
Not sure if it was your intent, but your post actually makes a better argument for truing/lapping the face then not.
Now, to be fair, I didn't do a great job posing this question on the onset. I am referring to forged, run of the mill receivers. Those with precision billet receivers can ignore this post.
Your suggestion to "float" the barrel strikes me a contrary to the goals of precision. (1) I don't want the barrel to move in the receiver. All of the sighting systems for this platform attach to the receiver. If the barrel moves it will effect POI either shot to shot or session to session, all to me are bad. (2) the discussion of anodizing on the face of the receiver is a mute point to me. If anodizing is the only thing keeping from wearing out that face there are bigger problems. I would suggest that argument is accurate for the interior, but not on these parts.
All bolts wear in eventually, if the barrel is not sitting true to the bore of the receiver this is more of a problem, thus why I am starting to believe truing the face is important.
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Floating a barrel simply means that other than its point of attachement to the receiver, it contacts nothing else.
Take a plane jane run of the mill M16A2 as the example. The front sight assembly retains the hand guards in the front. The slip ring retains them in the rear. The barrel is directly supporting the handguards. Now sling into this in any position. If you vary the tension of the sling, your position, anything the slightest little bit, you have the potential to cause a wandering point of impact.
Why? Cause your bending on that barrel with your entire upper torso.
Now, take an imaginary saw and chop off the front of the handguard so that it's dangling in space. Attach your sling swivel to that handguard. At this point there are only two items the barrel is in contact with. The front ring on the upper receiver and the gas tube. You squash yourself back into position and wrench on that sling all you want. The barrel is static. It's not being directly influenced by the tension.
The arguement could be made that if you crank on it hard enough, you could distort the front of the receiver. Ok, I'll give into that. However this is a well documented, well rehearsed, well established practice performed by gunsmiths on every National Match Service rifle used in formal NRA Highpower SR competition. It's nothing new or earth shattering. Been this way for over 20 years.
The point of this process is to allow the barrel to whip around, wiggle, swell, whatever (or the magical internet term "harmonic") however it wants to. What you don't want is artificial influence from an outside source (that would be YOU, the shooter) causing it to behave one way on shot 1 and then another on shot 2, etc... Assuming your ammunition is well prepared means the barrel will respond in a predictable manner from one shot to the next. That DOES encourage a rifle to be MORE accurate.
I can tell you this after 20 years of doing this: If you want to take the time to "true" and AR upper go for it. If it makes you feel good, then by all means. Someday your going to be shooting this rifle and some snot nozed teenager is going to be dressed up in a highpower coat practicing for state, regional, nationals, whatever.
The kid will kick your ass royally. (cause that's what little bastages with good eyes and a Daddy that doesn't care what it costs-DO. They make us mortals look like fools)
Your going to ask what billet, whiz bang upper, trued by God himself, setup is he/she running. Your world is going to fall apart when they tell you its a rack bought National Match gun build by Rock River, Compass Lake, Accuracy Speaks, Mark Chanlynn, who ever.
Bet a buck nobody trued that upper.
Good luck and have fun.
C.
Take a plane jane run of the mill M16A2 as the example. The front sight assembly retains the hand guards in the front. The slip ring retains them in the rear. The barrel is directly supporting the handguards. Now sling into this in any position. If you vary the tension of the sling, your position, anything the slightest little bit, you have the potential to cause a wandering point of impact.
Why? Cause your bending on that barrel with your entire upper torso.
Now, take an imaginary saw and chop off the front of the handguard so that it's dangling in space. Attach your sling swivel to that handguard. At this point there are only two items the barrel is in contact with. The front ring on the upper receiver and the gas tube. You squash yourself back into position and wrench on that sling all you want. The barrel is static. It's not being directly influenced by the tension.
The arguement could be made that if you crank on it hard enough, you could distort the front of the receiver. Ok, I'll give into that. However this is a well documented, well rehearsed, well established practice performed by gunsmiths on every National Match Service rifle used in formal NRA Highpower SR competition. It's nothing new or earth shattering. Been this way for over 20 years.
The point of this process is to allow the barrel to whip around, wiggle, swell, whatever (or the magical internet term "harmonic") however it wants to. What you don't want is artificial influence from an outside source (that would be YOU, the shooter) causing it to behave one way on shot 1 and then another on shot 2, etc... Assuming your ammunition is well prepared means the barrel will respond in a predictable manner from one shot to the next. That DOES encourage a rifle to be MORE accurate.
I can tell you this after 20 years of doing this: If you want to take the time to "true" and AR upper go for it. If it makes you feel good, then by all means. Someday your going to be shooting this rifle and some snot nozed teenager is going to be dressed up in a highpower coat practicing for state, regional, nationals, whatever.
The kid will kick your ass royally. (cause that's what little bastages with good eyes and a Daddy that doesn't care what it costs-DO. They make us mortals look like fools)
Your going to ask what billet, whiz bang upper, trued by God himself, setup is he/she running. Your world is going to fall apart when they tell you its a rack bought National Match gun build by Rock River, Compass Lake, Accuracy Speaks, Mark Chanlynn, who ever.
Bet a buck nobody trued that upper.
Good luck and have fun.
C.
I have only trued a couple of uppers and that was because the customers complained about grouping issues.
Both rifles exhibited a visually skewed barrel/receiver relationship.
When mounted between centers runout was apparent on the assembled uppers.
Barrels showed no runout between centers.
One reciever was an Aero, IIRC the other was Core15.
Both required .010-.015 to clean up.
Both shot well afterwards and it did correct the issue.
It has its place but only when it is absolutely required.
I will side with Chad on this one. Anodized Aluminum is like a loaf of bread, it is a relatively soft core with a hard outer surface.
An AR barrel is held in place by the compressive forces of the nut tightened against the extension "ring". The backside of the extension "ring" bears on the upper. Remove that hard coat of anodizing and you are compressing tempered steel against relatively soft aluminum.
Lab experiment time- take a 1/2" thick plate of aluminum, drill a 3/8" hole through it. Now take a 3/8" bolt, hardened washer and nut and assemble them on the plate.
Now take that assembly and with a hammer pound on the head of the bolt a couple of hundred times.
Disassemble it and observe the aluminum where the washer was.
The exact same forces are enacted on the receiver ring when the rifle is fired.
A clean trigger, proper assembly and quality components will go farther for an accurate, consistent rifle than such work.
Both rifles exhibited a visually skewed barrel/receiver relationship.
When mounted between centers runout was apparent on the assembled uppers.
Barrels showed no runout between centers.
One reciever was an Aero, IIRC the other was Core15.
Both required .010-.015 to clean up.
Both shot well afterwards and it did correct the issue.
It has its place but only when it is absolutely required.
I will side with Chad on this one. Anodized Aluminum is like a loaf of bread, it is a relatively soft core with a hard outer surface.
An AR barrel is held in place by the compressive forces of the nut tightened against the extension "ring". The backside of the extension "ring" bears on the upper. Remove that hard coat of anodizing and you are compressing tempered steel against relatively soft aluminum.
Lab experiment time- take a 1/2" thick plate of aluminum, drill a 3/8" hole through it. Now take a 3/8" bolt, hardened washer and nut and assemble them on the plate.
Now take that assembly and with a hammer pound on the head of the bolt a couple of hundred times.
Disassemble it and observe the aluminum where the washer was.
The exact same forces are enacted on the receiver ring when the rifle is fired.
A clean trigger, proper assembly and quality components will go farther for an accurate, consistent rifle than such work.
Brownell's has made a fortune selling that stupid tool and a tub of aluminum oxide paste to the unwashed masses. Sounds like PTG is on scheme. God love 'em for finding a way to separate fools and their money...
RRA doesn't surprise me. When a national match RRA needs 8moa of windage to zero from the box speaks of quality. Went to the store and looked at another after I knew what to look for(canted front sight) and that one was off as well. I learned alot since then.
Oh-and the off the shelf Armalite NM-mechanical zero is my zero for wind with factory FGMM.
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