View Full Version : Facing an upper receiver ?
I have used the search function on this with very little information gathered other than it is a feel good measure.
I have a BCM4 upper on the way with a Brownells facing tool also.
Thinking facing is a good thing to have receiver face square for proper barrel installation and equal bolt lug engagement.
Am I on the right track ?
Building a precision upper for bench rest and prone shooting.
Taking my time on this build, maybe a year.
Currently looking at barrels, specifically the Lija at this time.
Clarence
rcoodyar15
07-14-15, 19:36
many will tell you it is not necessary. I will tell you it is cheap insurance. Hell I just did a mur upper receiver and lapping the face will tell the tale. It was not square.
For a precision upper I would definitely do it. When it comes time to time the barrel nut and the gas tube and get the barrel nut torque where you want it lapping is your friend.
I've wondered what kind of real-world difference this makes. I have an upper where the rear BUS is almost all the way to the left. If I lapped the upper would it make enough difference that the BUS would come back more towards the center?
Toyoland66
07-15-15, 12:24
If the face of the receiver isn't square then what are the odds the threads are. If the threads aren't square you may have full contact between the barrel and face of receiver after lapping, but you will still have uneven pressure from the barrel nut.
rcoodyar15
07-15-15, 13:07
I've wondered what kind of real-world difference this makes. I have an upper where the rear BUS is almost all the way to the left. If I lapped the upper would it make enough difference that the BUS would come back more towards the center?
I am sure there will be improvement. Why don't you try it and get back to us. Give the doubters a little feedback.
brownells has the kit and it is really pretty inexpensive.
I am sure there will be improvement. Why don't you try it and get back to us. Give the doubters a little feedback.
brownells has the kit and it is really pretty inexpensive.
Honestly I hate to go to the trouble of pulling the upper apart just for that, but at the same time I'm curious what would the results would be from an academic standpoint. I'm thinking of rebarreling this upper before too long so I might lap it then, but putting it back together with a different barrel wouldn't really tell us anything for sure.
jackblack73
07-15-15, 13:50
Since BCM started machining their own uppers for a tighter barrel extension fit I wonder if they also machine them so the face is true. Although I don't know how subsequent anodizing would affect that.
Some of the more experienced shooters here who've tried it claim it helps. Like SteveL, I'm not pulling a gun apart to do it, but if I get back into putting uppers together, I'm buying the tool.
Wast of time and money. Will you also true the mounted barrel extension flange? You gonna true the nut? Wiggle the bolt inside the carrier and tell me if it is a tight fit? Wiggle the carrier inside of the receiver tell me how tight it is. There is slack everywhere. If there wasn't the rifle wouldn't run very long. Trying to true a receiver with a hand tool is a waste of time. You might even make it worse.
rcoodyar15
07-15-15, 17:17
Wast of time and money. Will you also true the mounted barrel extension flange? You gonna true the nut? Wiggle the bolt inside the carrier and tell me if it is a tight fit? Wiggle the carrier inside of the receiver tell me how tight it is. There is slack everywhere. If there wasn't the rifle wouldn't run very long. Trying to true a receiver with a hand tool is a waste of time. You might even make it worse.
I guess everyone is entitled to an opinion
and what are you basing that opinion on?
have you ever lapped one?
Personally I like my barrel pointed straight and fully supported all the way around at the receiver/barrel extension interface.
I think it has a lot to do with what you are trying to accomplish with the gun. If it is just your typical SHTF AR then who cares. But if you are using heavy match barrels and trying to shoot tiny groups then every little bit helps.
I guess everyone is entitled to an opinion
and what are you basing that opinion on?
have you ever lapped one?
Personally I like my barrel pointed straight and fully supported all the way around at the receiver/barrel extension interface.
I think it has a lot to do with what you are trying to accomplish with the gun. If it is just your typical SHTF AR then who cares. But if you are using heavy match barrels and trying to shoot tiny groups then every little bit helps.
Read my post again and tell me what it stands a chance of doing other than f---ing something up. I like Brownells but a lot of they stuff they sell is a joke. The lapping tool is one of them. Did you believe all of the claims for HP gain printed in the JC Whitney catalog?? Truth is... If you blow enough smoke it will find it's way up someones ass. It's called marketing!
Read my post again and tell me what it stands a chance of doing other than f---ing something up. I like Brownells but a lot of they stuff they sell is a joke. The lapping tool is one of them. Did you believe all of the claims for HP gain printed in the JC Whitney catalog?? Truth is... If you blow enough smoke it will find it's way up someones ass. It's called marketing!
While I'm not convinced lapping the upper will turn my rifle into a 1/2" gun, I also don't see how it would screw anything up.
rcoodyar15
07-15-15, 19:33
Read my post again and tell me what it stands a chance of doing other than f---ing something up. I like Brownells but a lot of they stuff they sell is a joke. The lapping tool is one of them. Did you believe all of the claims for HP gain printed in the JC Whitney catalog?? Truth is... If you blow enough smoke it will find it's way up someones ass. It's called marketing!
well from your reply I assume you have absolutely no experience lapping a receiver face. You have nothing to base your opinion on. Probably something you heard somewhere on the internet.
and I would assume from your reply that you have no intention of ever trying it.
different strokes for different folks
The problem is that truing just one surface of a two surface union doesn't guarantee perfect mating - there is interface between the threads on the barrel nut and receiver, the threads on the barrel and barrel extension, and the shoulder of the barrel extension and the lapped front of the receiver.
To me it would make more sense to remove the index pin from the barrel extension and lap the two surfaces together then replace the pin. The problem is that it would be hard to keep lapping compound out of the throat of the receiver and the movement of the lapping process would probably increase the tolerances in the extension receiver throat area.
I don't think the Brownell's tool would hurt much, it may help some.
Something Sully shows at his armorer courses is the difference in dimension of different receivers (upper and lower) - often dependent on how the person doing the machining clamped the blank into the machine. The engineering feat of mass produced weapons is making parts (lowers and uppers, lpk's, bolts, bolt carriers, etc.) within +/- tolerances so that random parts taken from a bin fit together to make a functioning weapon with acceptable accuracy and function. For that reason big gains in accuracy don't often come from one simple operation.
JM .02
...I don't think the Brownell's tool would hurt much, it may help some.
Something Sully shows at his armorer courses is the difference in dimension of different receivers (upper and lower) - often dependent on how the person doing the machining clamped the blank into the machine. The engineering feat of mass produced weapons is making parts (lowers and uppers, lpk's, bolts, bolt carriers, etc.) within +/- tolerances so that random parts taken from a bin fit together to make a functioning weapon with acceptable accuracy and function. For that reason big gains in accuracy don't often come from one simple operation.
JM .02
The collection of "random parts taken from a bin" seldom leads to really accurate results, however. Isn't that why a really good 1911 will be full of hand-fitted parts? Sometimes costing as much as or more than the original gun? "Acceptable accuracy and function" mean different things to different people.
And while if may be true that "big gains in accuracy don't often come from one simple operation", those big gains can come from a series of small operations, all working to the same end. Any hand loader can tell you how large a difference can be had from a small
.2 grain change in loading, or a small change in bullet depth, or changing primers or brass. It can and does make the difference between .5 MOA and 1.5 MOA.
In light of these things, why would you not do something so easy and simple that can nudge you toward your goal?
I recently completed an upper built with a BCM receiver. They certainly nailed the tighter fit for the barrel extension. But the front of the receiver was not perpendicular to the bore. It is now...
rcoodyar15
07-16-15, 05:01
The collection of "random parts taken from a bin" seldom leads to really accurate results, however. Isn't that why a really good 1911 will be full of hand-fitted parts? Sometimes costing as much as or more than the original gun? "Acceptable accuracy and function" mean different things to different people.
And while if may be true that "big gains in accuracy don't often come from one simple operation", those big gains can come from a series of small operations, all working to the same end. Any hand loader can tell you how large a difference can be had from a small
.2 grain change in loading, or a small change in bullet depth, or changing primers or brass. It can and does make the difference between .5 MOA and 1.5 MOA.
In light of these things, why would you not do something so easy and simple that can nudge you toward your goal?
I recently completed an upper built with a BCM receiver. They certainly nailed the tighter fit for the barrel extension. But the front of the receiver was not perpendicular to the bore. It is now...
I had the same experience with my first precision build. A top of the line receiver set. Gun wouldn't hold groups. I noticed my windage was well off dead center. Tried a lot of things and then finally read about the brownells lapping tool. Took it apart and lapped the face and things straightened right up. It also makes timing barrel nut torque and gas tubes a breeze.
I wonder when someone is going to do an AR like Tony Kidd has done the 10/22. He did away with the slip fit and actually threaded the barrel into the receiver. Bet that would make a difference in precision.
BufordTJustice
07-16-15, 09:08
I have used the search function on this with very little information gathered other than it is a feel good measure.
I have a BCM4 upper on the way with a Brownells facing tool also.
Thinking facing is a good thing to have receiver face square for proper barrel installation and equal bolt lug engagement.
Am I on the right track ?
Building a precision upper for bench rest and prone shooting.
Taking my time on this build, maybe a year.
Currently looking at barrels, specifically the Lija at this time.
Clarence
I do it using the same tool. Last one was a blem BCM upper (pre BCM4 with the tighter tolerances).
The BUIS and aimpoint were virtually dead on for windage after lapping the receiver face. Does this bear strongly on reliability? Likely not.
However, can ensuring that the lugs of the bolt bear equally on the barrel extension equal greater reliability? It sure as hell can't hurt.
The one potential problem that no one has mentioned is that if you take too much material off the receiver face, the barrel extension could sit back too far into the receiver when assembled.
If you have M4 style feed ramps where the extension feed ramps and receiver feed ramps match up perfectly, lapping a receiver face could create a ledge that could affect how well the cartridge (bullet tip) feeds into the chamber. If you already have a little bit of a ledge before lapping, lapping could make it worse.
Do I lap my receiver faces? Sometimes I do and sometimes I don't. It depends on my mood, the gun I am building, how much time I have, etc. But before I lap a receiver, I always slide the barrel into the upper to see if the fee ramps match up OK or if there will be a problem.
Joe Mamma
rcoodyar15
07-16-15, 13:51
The one potential problem that no one has mentioned is that if you take too much material off the receiver face, the barrel extension could sit back too far into the receiver when assembled.
If you have M4 style feed ramps where the extension feed ramps and receiver feed ramps match up perfectly, lapping a receiver face could create a ledge that could affect how well the cartridge (bullet tip) feeds into the chamber. If you already have a little bit of a ledge before lapping, lapping could make it worse.
Do I lap my receiver faces? Sometimes I do and sometimes I don't. It depends on my mood, the gun I am building, how much time I have, etc. But before I lap a receiver, I always slide the barrel into the upper to see if the fee ramps match up OK or if there will be a problem.
Joe Mamma
I take very little off in reality. Lap a little and look. if part is shiny and part is still black I lap a little more. I just do it until the entire face is shiny. I have yet to do one that was shiny all the way around the first time I looked.
Now when I am lapping to time the barrel nut torque and gas tube I might take off a little more but it is still very little.
I wouldn't lap if I was assembling a normal AR with a standard barrel. Not worth the trouble.
but if I am installing a heavy match barrel and expect tiny groups then I will lap.
I will certainly check the feed ramps in the future.
I had the same experience with my first precision build. A top of the line receiver set. Gun wouldn't hold groups. I noticed my windage was well off dead center. Tried a lot of things and then finally read about the brownells lapping tool. Took it apart and lapped the face and things straightened right up. It also makes timing barrel nut torque and gas tubes a breeze.
I wonder when someone is going to do an AR like Tony Kidd has done the 10/22. He did away with the slip fit and actually threaded the barrel into the receiver. Bet that would make a difference in precision.
I don't think threading a barrel extension into an upper would have an appreciable effect, particularly if it's a similar issue with the receiver not being square/perpendicular to the bore.
There are plenty of slip-fit configurations that are very accurate such as the DTA rifle. And, as you know, the 10/22 is not exactly the same analog. It's a slip fit with only the two lightly torqued screws in the v-bock securing the barrel to the receiver. An AR barrel extension does slip into the upper (better if it's a snug fit), but torqued and held in place to a secure fit with the barrel nut.
Changes in the design of the barrel extension, bolt and chamber would have a better effect resulting in tighter bolt tolerances, a shorter throat, and tighter neck dimensions. Of course, that ain't going to cut it with anything but a precision rig and not conducive to a fighting rifle that has to feed and extract all sorts of ammo varieties at variable sustained rates of fire.
The collection of "random parts taken from a bin" seldom leads to really accurate results, however. Isn't that why a really good 1911 will be full of hand-fitted parts? Sometimes costing as much as or more than the original gun? "Acceptable accuracy and function" mean different things to different people.
And while if may be true that "big gains in accuracy don't often come from one simple operation", those big gains can come from a series of small operations, all working to the same end. Any hand loader can tell you how large a difference can be had from a small
.2 grain change in loading, or a small change in bullet depth, or changing primers or brass. It can and does make the difference between .5 MOA and 1.5 MOA.
In light of these things, why would you not do something so easy and simple that can nudge you toward your goal?
I recently completed an upper built with a BCM receiver. They certainly nailed the tighter fit for the barrel extension. But the front of the receiver was not perpendicular to the bore. It is now...
I don't want you to think I was saying don't do it, I was merely pointing out that it may not do wonders, at no point did my post say, as others did, hey you are wasting your time. I was writing that as a guy who has spent hours rubbing clutch pressure plates on my surface plate to get a smoother engagement on our racing kart clutches - it didn't make us winners, but every bit helps, I don't think I wasted my time on that.
FWIW, I don't lap any receivers as I don't trust the tool or the method. It would be better served setup properly in a lathe and I've had a couple done by smiths who were familiar with the setup. That's sort of a PITA, of course. What I do now is pick a known, quality upper, install the barrel and barrel nut torqued to 40 lb ft and take it to the range. If it's not grouping properly I'll increase the torque 10 ft lbs and shoot again until I've hit an upper limit of 70 lb ft (sometimes 80 if trending in the right direction). If it's still not grouping properly, I'll try a different upper and repeat the process. I use two handguards with barrel nuts that do not require indexing: a 13" Geissele MK2 or a 12" DD Mother-Effer (MFR). These have pretty generous internal dimensions for most gas block and barrel setups and in the case of the Daniel Defense, it's short enough that a rifle-length gas block will extend beyond the rail.
Do not forget to factor the length of the barrel nut tool into the torque equation.
.
The problem I see with lapping the upper barrel face is if you cut through the anodizing you now have bare aluminum in contact with steel, and the potential for corrosion to set in.
For match guns with someone who can hold the X ring at 600 yards, yeah, it is probably worth it. For the average duty weapon, little point.
rcoodyar15
07-17-15, 09:12
FWIW, I don't lap any receivers as I don't trust the tool or the method. It would be better served setup properly in a lathe and I've had a couple done by smiths who were familiar with the setup. That's sort of a PITA, of course. What I do now is pick a known, quality upper, install the barrel and barrel nut torqued to 40 lb ft and take it to the range. If it's not grouping properly I'll increase the torque 10 ft lbs and shoot again until I've hit an upper limit of 70 lb ft (sometimes 80 if trending in the right direction). If it's still not grouping properly, I'll try a different upper and repeat the process. I use two handguards with barrel nuts that do not require indexing: a 13" Geissele MK2 or a 12" DD Mother-Effer (MFR). These have pretty generous internal dimensions for most gas block and barrel setups and in the case of the Daniel Defense, it's short enough that a rifle-length gas block will extend beyond the rail.
Do not forget to factor the length of the barrel nut tool into the torque equation.
.
different strokes for different folks
it works for me but I can understand your theoretical arguments
FWIW, I don't lap any receivers as I don't trust the tool or the method. It would be better served setup properly in a lathe and I've had a couple done by smiths who were familiar with the setup. That's sort of a PITA, of course. What I do now is pick a known, quality upper, install the barrel and barrel nut torqued to 40 lb ft and take it to the range. If it's not grouping properly I'll increase the torque 10 ft lbs and shoot again until I've hit an upper limit of 70 lb ft (sometimes 80 if trending in the right direction). If it's still not grouping properly, I'll try a different upper and repeat the process. I use two handguards with barrel nuts that do not require indexing: a 13" Geissele MK2 or a 12" DD Mother-Effer (MFR). These have pretty generous internal dimensions for most gas block and barrel setups and in the case of the Daniel Defense, it's short enough that a rifle-length gas block will extend beyond the rail.
Do not forget to factor the length of the barrel nut tool into the torque equation.
.The point was recently made in another thread that you are supposed to have the barrel nut tool in line, and that's taken into account with the torque values given.
Great discussion so far.
Well, I have obtained the low cost components of the upper so far.
BCM4 upper, BCM bcg and mod4 ch.
I am going to face the receiver with the Brownells tool and take pic's .
In theory, the tighter barrel extension and squaring the receiver will take care of the barrel installation.
No timing of the barrel nut involved cause it will be free floated.
Not worried about the barrel being set back to cause feed ramp issues.
Upper will be single loaded only when complete.
(please do not bring up slam fires...)
Next is barrel, gas tube and gas block and then free float tube.
Clarence
Great discussion so far.
Well, I have obtained the low cost components of the upper so far.
BCM4 upper, BCM bcg and mod4 ch.
I am going to face the receiver with the Brownells tool and take pic's .
In theory, the tighter barrel extension and squaring the receiver will take care of the barrel installation.
Put the barrel in the upper and slide it all the way in firmly. First observe, then measure the gap on all sides at the flange.
If it's so small you cannot measure the difference with a feeler gauge, then I would not face it.
If the difference is noticeable, the upper is out of spec and I'd exchange it.
Personally, I find the facing argument unicorn tears from smiths. Seen too many rifles shoot well without it and one mfg/designer I trust has explained to my satisfaction how the design allows for slight deformation of the AL face under the barrel nut torque. IE: unequal bolt thrust is a myth unless the upper is significantly out of spec. Especially true with tight extension to upper fit, the extension cannot cant!
With in spec parts, this is wasted effort on carbines. $600 bull barrel with $1k glass, shooting match ammo, I might would consider it.
However, can ensuring that the lugs of the bolt bear equally on the barrel extension equal greater reliability?
Lapping the extension on the upper receiver ensures no such thing. You'd have to assume that the bolt and barrel extension are perfect. That lapping tool is for shade tree gunsmiths. The process is appealing to a certain crowd because there's nothing else that can be smith'd in the shade of said tree to really improve accuracy.
Lapping the extension on the upper receiver ensures no such thing. You'd have to assume that the bolt and barrel extension are perfect. That lapping tool is for shade tree gunsmiths. The process is appealing to a certain crowd because there's nothing else that can be smith'd in the shade of said tree to really improve accuracy.
Finally someone with common sense... I love the "shade tree" reference. I'll bet 99.9% of those who buy the lapping tool have NO way to determine if the receiver face was square before lapping or after. Shade tree gunsmiths..... I love it!
Finally someone with common sense... I love the "shade tree" reference. I'll bet 99.9% of those who buy the lapping tool have NO way to determine if the receiver face was square before lapping or after. Shade tree gunsmiths..... I love it!
Agreed. Additionally, one has to guarantee the barrel nut is square and that internal dimensions of the receiver are sufficiently tight & square to ensure the lapping face of the tool of the tool is correctly setup.
BufordTJustice
07-18-15, 16:19
Lapping the extension on the upper receiver ensures no such thing. You'd have to assume that the bolt and barrel extension are perfect. That lapping tool is for shade tree gunsmiths. The process is appealing to a certain crowd because there's nothing else that can be smith'd in the shade of said tree to really improve accuracy.
So, you have said tool in your physical custody and have measured it to be of shade tree specifications?
Also, how can bringing a non-true receiver face BACK into spec-range not provide for more even distribution of recoil forces upon the bolt lugs, as long as they, too, are in-spec?
rcoodyar15
07-18-15, 16:41
so those of you who do not believe in lapping a receiver face are free to not lap.
If you have never tried it then why do you think we should value your opinion?
Personally I think all this In spec. Mil spec is all BS. Doesn't make the gun shoot better. Just makes it easier to control the low bid manufacturing process.
this is like arguing over neck turning.
So, you have said tool in your physical custody and have measured it to be of shade tree specifications?
Also, how can bringing a non-true receiver face BACK into spec-range not provide for more even distribution of recoil forces upon the bolt lugs, as long as they, too, are in-spec?
All he is saying is that the tool and method are shade tree at best. I have no problem checking and correcting the face of the receiver if you are capable of doing it. I have problem with one size fits all shade tree methods. The only way the Brownell's tool could come close to working is if the pilot on it was perfectly sized for your receiver. Read the reviews if you doubt me. A professional smith would turn a bar the exact diameter or the receiver bore, sweat the receiver onto it and indicate the face. Trim it if necessary. He would also check the head space after trimming it. I love Brownell's but they do sell a lot of shade tree crap.
All he is saying is that the tool and method are shade tree at best. I have no problem checking and correcting the face of the receiver if you are capable of doing it. I have problem with one size fits all shade tree methods. The only way the Brownell's tool could come close to working is if the pilot on it was perfectly sized for your receiver. Read the reviews if you doubt me. A professional smith would turn a bar the exact diameter or the receiver bore, sweat the receiver onto it and indicate the face. Trim it if necessary. He would also check the head space after trimming it. I love Brownell's but they do sell a lot of shade tree crap.
A professional should know what is necessary and what isn't. Jesus Christ, I hold tenths on a daily basis, sweating shit in is overkill for anything to do with what they are talking about.
If your truing set-up doesn't look something like one of these, your just rubbing off anodizing.
34232
34233
34234
Precision modification requires precision tools.
BufordTJustice
07-18-15, 17:36
If your truing set-up doesn't look something like one of these, your just rubbing off anodizing.
34232
34233
34234
Precision modification requires precision tools.
If you're doing much more than removing a few thousandths, you're going to be staring at the barrel extension feed ramps over-hanging the receiver feed ramps.
I've used the Brownells tool on 27 different receivers (and counting) and it has been a very tight, slip-fit affair in every single one. I've had to liberally apply EP grease to the bore of the receiver and tool for every upper receiver so far, or else you couldn't even get the tool in the receiver. You have obviously not used the tool.
I'm going to assume you're aware of the issues of barrel extension protrusion overriding the feedramps in the receiver, as I have NEVER had to remove so much material as is seen in the photos you posted.
I have, however, encountered the by-product of overzealous lathe work. The use of quality machines in a shop environment is NOT in any way a guarantee against improper machining. Tooling wears, machining rates vary, materials quality can vary (7075 machines quite differently from 6061), etc.
BufordTJustice
07-18-15, 17:41
All he is saying is that the tool and method are shade tree at best. I have no problem checking and correcting the face of the receiver if you are capable of doing it. I have problem with one size fits all shade tree methods. The only way the Brownell's tool could come close to working is if the pilot on it was perfectly sized for your receiver. Read the reviews if you doubt me. A professional smith would turn a bar the exact diameter or the receiver bore, sweat the receiver onto it and indicate the face. Trim it if necessary. He would also check the head space after trimming it. I love Brownell's but they do sell a lot of shade tree crap.
Product reviews must be taken with a grain of salt. When the RRA trigger gets glowing reviews (you know, the one that has a long history of failing with only light use), it's pretty clear the qualifications of those making said reviews.
If you're doing much more than removing a few thousandths, you're going to be staring at the barrel extension feed ramps over-hanging the receiver feed ramps.
I've used the Brownells tool on 27 different receivers (and counting) and it has been a very tight, slip-fit affair in every single one. I've had to liberally apply EP grease to the bore of the receiver and tool for every upper receiver so far, or else you couldn't even get the tool in the receiver. You have obviously not used the tool.
I'm going to assume you're aware of the issues of barrel extension protrusion overriding the feedramps in the receiver, as I have NEVER had to remove so much material as is seen in the photos you posted.
I have, however, encountered the by-product of overzealous lathe work. The use of quality machines in a shop environment is NOT in any way a guarantee against improper machining. Tooling wears, machining rates vary, materials quality can vary (7075 machines quite differently from 6061), etc.
I buy quality components and don't sweat this issue. That being said, let's just agree to disagree. I sure hope you made good money on those 27 receivers. I'd hate to think your time isn't worth anything.
BufordTJustice
07-18-15, 17:46
I buy quality components and don't sweat this issue. That being said, let's just agree to disagree. I sure hope you made good money on those 27 receivers. I'd hate to think your time isn't worth anything.
I do them for friends. They're all patrol carbines for local and state LEOs... many of them on specialty teams. I don't charge.
I already know the quality and value of my work. I don't need your approval or validation.
rcoodyar15
07-18-15, 18:02
I do them for friends. They're all patrol carbines for local and state LEOs... many of them on specialty teams. I don't charge.
I already know the quality and value of my work. I don't need your approval or validation.
Man the internet is entertaining
people have no Idea what they are talking about and they are experts
and people who do it all the time are shade tree gunsmiths
Somewhere in there someone even said that after you lap the receiver face you better check headspace. :confused:
You really have to filter your information on these forums. Opinion can become fact pretty quickly if you can convince enough that what you say it true.
BufordTJustice
07-18-15, 18:06
Man the internet is entertaining
people have no Idea what they are talking about and they are experts
and people who do it all the time are shade tree gunsmiths
Somewhere in there someone even said that after you lap the receiver face you better check headspace. :confused:
You really have to filter your information on these forums. Opinion can become fact pretty quickly if you can convince enough that what you say it true.
Just so we're all clear, this process has no effect on headspace.
There is no doubt truing the face of the receiver on a bolt action rifle, truing the threads, etc., does a great deal to improve accuracy. You would be hard pressed to find someone who claims it won't have an effect on accuracy.
I have been following discussions on the merits of lapping the face of an AR receiver for a few years and opinions always seem to be split.
I have assembled a few AR-15 rifles over the years that would shoot 1/2 MOA at 300 yards without lapping the receiver face.
I am going to wait a bit longer before buying the tool.
rcoodyar15
07-18-15, 18:34
Just so we're all clear, this process has no effect on headspace.
no kidding! you don't even need the barrel in the receiver to check headspace. No way possible for facing the receiver to effect it.
rcoodyar15
07-18-15, 18:38
There is no doubt truing the face of the receiver on a bolt action rifle, truing the threads, etc., does a great deal to improve accuracy. You would be hard pressed to find someone who claims it won't have an effect on accuracy.
I have been following discussions on the merits of lapping the face of an AR receiver for a few years and opinions always seem to be split.
I have assembled a few AR-15 rifles over the years that would shoot 1/2 MOA at 300 yards without lapping the receiver face.
I am going to wait a bit longer before buying the tool.
1/2 MOA AR now that is good. It is consistent?
Can you put 5 five shot groups on this target at 100 yards of 1/2" or less
http://www.turners.com/prodimages/3503-DEFAULT-l.jpg
elephantrider
07-18-15, 18:56
Man the internet is entertaining
people have no Idea what they are talking about and they are experts
and people who do it all the time are shade tree gunsmiths
Somewhere in there someone even said that after you lap the receiver face you better check headspace. :confused:
You really have to filter your information on these forums. Opinion can become fact pretty quickly if you can convince enough that what you say it true.
Why don't you post the before and after of one of your re-faced receivers using a dial indicator showing just how true and square everything is to the bore of the receiver. Wouldn't that quiet the doubters and 'show me' types?
While you're at it you can check the two faces of the barrel extension that interface with the upper receiver face and the barrel nut. Then check the OD of the barrel extension against the center line of the rifle bore, and lets not forget to the check threads of the upper receiver and barrel nut as well. If any of those are out as much as the receiver face, should they not be trued up as well?
BufordTJustice
07-18-15, 19:12
no kidding! you don't even need the barrel in the receiver to check headspace. No way possible for facing the receiver to effect it.
Roger that. Just wanted to make sure everyone was on the same page.
rcoodyar15
07-18-15, 19:19
Why don't you post the before and after of one of your re-faced receivers using a dial indicator showing just how true and square everything is to the bore of the receiver. Wouldn't that quiet the doubters and 'show me' types?
While you're at it you can check the two faces of the barrel extension that interface with the upper receiver face and the barrel nut. Then check the OD of the barrel extension against the center line of the rifle bore, and lets not forget to the check threads of the upper receiver and barrel nut as well. If any of those are out as much as the receiver face, should they not be trued up as well?
Us Shade Tree Gunsmiths just don't go for all that dial indicator stuff. We go by our gut.
you are welcome to get one of your machinist buddies to do those test if you are really interested though. Please give us a report on how it turns out.
I wonder how a discussion on lapping scope rings would go with this crowd.
We machine the main bore and the face of the receiver/threads off the rail itself. I don't know how others do it, but using the rail as a fixture point keeps everything perfectly square to the bore, in relation to the rail.
Ryan
We machine the main bore and the face of the receiver/threads off the rail itself. I don't know how others do it, but using the rail as a fixture point keeps everything perfectly square to the bore, in relation to the rail.
Ryan
And it'd still show not true with the lapping tool. That's where the issue arises. How accurate is the lapping tool and how accurate is the upper? Even with your fixturing system, it probably doesn't keep it much more square than a half thou, but that's just a wild assumption on my part. Any difference is going to show. I seriously doubt a half thou matters in this circumstance for a non super-precision rig.
I might buy the tool just to see. I was going to make one at work so I knew it was square.
Feel free to send an upper, I'll measure it best I can LOL
I've wondered what kind of real-world difference this makes. I have an upper where the rear BUS is almost all the way to the left. If I lapped the upper would it make enough difference that the BUS would come back more towards the center?
I am sure there will be improvement. Why don't you try it and get back to us. Give the doubters a little feedback.
brownells has the kit and it is really pretty inexpensive.
Just noticed this question and comment... The idea that the Brownell tool will help center a full left windage adjustment is just silly.
The math does not support this type of misalignment being from the face. And in fact, if the upper bore, extension, and barrel are in spec, this type of windage problem would not be from those components.
I'd be suspecting a canted front sight base or similar.
Barrel extension to upper bore fit has the biggest impact on alignment. The flange/ face fit can only impact this as much as the extension can cant.
You might be able to relieve or equalize stress on the flange/extension or change barrel resonance stuff. But for a carbine??? Waste of time.
And it'd still show not true with the lapping tool. That's where the issue arises. How accurate is the lapping tool and how accurate is the upper? Even with your fixturing system, it probably doesn't keep it much more square than a half thou, but that's just a wild assumption on my part. Any difference is going to show. I seriously doubt a half thou matters in this circumstance for a non super-precision rig.
I might buy the tool just to see. I was going to make one at work so I knew it was square.
Feel free to send an upper, I'll measure it best I can LOL
You are correct on this... In most cases, (Or in the case of our upper) that lapping tool is most likely much less accurate than our Makino A51nx. You would probably be doing damage to the receiver by lapping it with that tool. But most people would just do it.. see that it took off material and say "See! It wasn't square to the bore!!" Your lapping tool sure wasn't as square in that bore as a 2 Million$$ Machining center, that's for sure!
Just something to think about.
Unless that lapping tool comes with a full set of Deltronics pins to use as a guide, in some cases it may be taking your upper out of square.
elephantrider
07-18-15, 22:58
Us Shade Tree Gunsmiths just don't go for all that dial indicator stuff. We go by our gut.
I didn't call you a 'Shade Tree Gunsmith,' or any kind of gunsmith for that matter. I get that you are going for sarcasm here, but it really does nothing to support your claims. As far as I can tell from your statements in this thread, you ARE just going by your gut. I haven't seen anything from you to substantiate your claims about the benefits of this lapping procedure, and you respond only with snark to a reasonable request. If you haven't done it, or don't have the ability to do it, just say so. You are making claims about benefits to barrel/windage alignment, and bolt alignment. These are things that can be measured, some of them quite easily, so for you to blow off these honest questions is more of a reflection on you.
you are welcome to get one of your machinist buddies to do those test if you are really interested though. Please give us a report on how it turns out.
Why would I devote the time and energy to this, you are the one making the claims after all? You are the one with the lapping fixture that is also advocating that others use it.
I wonder how a discussion on lapping scope rings would go with this crowd.
That is a bit off topic, so no comment.
elephantrider
07-18-15, 23:03
Just noticed this question and comment... The idea that the Brownell tool will help center a full left windage adjustment is just silly.
Yes, VERY silly, if you know anything about barrel making. There are a whole host of things that are MORE likely to cause windage issues than the upper receiver face.
1/2 MOA AR now that is good. It is consistent?
Can you put 5 five shot groups on this target at 100 yards of 1/2" or less
http://www.turners.com/prodimages/3503-DEFAULT-l.jpg
I never tried shooting this target, it would be difficult to shoot a good shot group with iron sights. The good rifles I assembled for high power rifle competition would shoot 1/2 MOA at 100 yards on a MR-31 target. Granted a lot of rifles I used for competition shot 3/4 MOA, but I had a few that would shoot 1/2 with good loads, a good sling and a proper shooting position.
Here's my .02 cents. I have assembled hundreds and more likely thousands of AR's. Some of the ones I have put together for myself and others have proven to be very accurate. Strangely it did not require some type of lapping tool or incessant amounts of man hours to accomplish.
rcoodyar15
07-19-15, 06:33
Here's my .02 cents. I have assembled hundreds and more likely thousands of AR's. Some of the ones I have put together for myself and others have proven to be very accurate. Strangely it did not require some type of lapping tool or incessant amounts of man hours to accomplish.
We all I can say is it works for me. Now if I was building your typical battle rifle I certainly would not bother.
the only ones I built have big long heavy barrels on them for precision shooting.
I have done forged and billet uppers this way.
the first one I built was a very high quality billet. Had a lot of trouble getting the gun to hold groups. POI shift.
I simply used the brownell lapping tool and that gun settled down and has been shooting under 1 MOA every since. I found during this procedure it was also easy to get exactly the barrel torque you wanted while timing your gas tube. So for me the benefit is twofold.
I have also noticed on one gun that my windage adjustment was well off center. After a little lapping it straightened right out.
I am sure there are better ways to accomplish this but I like doing it myself. The m16 was not designed to be a precision weapon. It was designed to be a functional, lightweight, cheaply mass produced assault rifle. The AR15 is just a civilian copy of it with just a few changes in the bolt carrier group to make it semiautomatic. It is like the old military .45. Loosely fitted for more reliability but there is a tradeoff with accuracy. We are doing things with it it was never meant to do.
rcoodyar15
07-19-15, 06:55
Here's my .02 cents. I have assembled hundreds and more likely thousands of AR's. Some of the ones I have put together for myself and others have proven to be very accurate. Strangely it did not require some type of lapping tool or incessant amounts of man hours to accomplish.
One in a thousand! awesome!
USMC_Anglico
07-19-15, 07:22
I would be hesitant to face a receiver with a hand tool. As has been stated earlier, you'll probably accomplish nothing, maybe even make it worse.
It stands to reason that custom smiths, who use precision lathes, machining equipment, etc. sometimes have difficulties facing bolt guns on occasion. What are the odds that using a hand tool (who knows what tolerances that it was made to) would get you the desired results? Juice doesn't seem worth the squeeze.
Rifle team shooters that I know (including Camp Perry winners) do not have AR's with faced receivers. They all tell me as far as equipment goes, the barrel is the most important. they also tell me even more important is the shooter..... I'm always working on that piece of the equation!
All lapping does is remove the protective anodizing off the face of the upper. Now, you have potential for galvanic corrosion with steel of bare aluminum.
In order for the lapping tool to spin freely inside the 1.000 + .002" bore in the upper, it has to be at least .004" undersize, or 0.996", so, at best the lapping tool only trues up the face to +/- .0035". The pitch diameter of the threads are, by the drawing, parallel to the 1.000 + .002" bore to .005".
Basically, the lapping tool does nothing.
Just out of curiosity, to the guy with the lathe, when you true the face, how much do you need to take off to true it up?
rcoodyar15
07-19-15, 08:05
I would be hesitant to face a receiver with a hand tool. As has been stated earlier, you'll probably accomplish nothing, maybe even make it worse.
It stands to reason that custom smiths, who use precision lathes, machining equipment, etc. sometimes have difficulties facing bolt guns on occasion. What are the odds that using a hand tool (who knows what tolerances that it was made to) would get you the desired results? Juice doesn't seem worth the squeeze.
Rifle team shooters that I know (including Camp Perry winners) do not have AR's with faced receivers. They all tell me as far as equipment goes, the barrel is the most important. they also tell me even more important is the shooter..... I'm always working on that piece of the equation!
Opinions Vary
http://www.longrangehunting.com/articles/building-accurate-ar-15-3.php
http://www.mdshooters.com/showthread.php?t=138045
All lapping does is remove the protective anodizing off the face of the upper. Now, you have potential for galvanic corrosion with steel of bare aluminum.
In order for the lapping tool to spin freely inside the 1.000 + .002" bore in the upper, it has to be at least .004" undersize, or 0.996", so, at best the lapping tool only trues up the face to +/- .0035". The pitch diameter of the threads are, by the drawing, parallel to the 1.000 + .002" bore to .005".
Basically, the lapping tool does nothing.
Just out of curiosity, to the guy with the lathe, when you true the face, how much do you need to take off to true it up?
I wire ejector pin holes with 2 tenths a side clearance and they spin just fine and still have some wobble to them. 4 thou is a bit much. And if the tool is held against one side, in your worst case 4 thou example, the shoulder will still be held square with the face. A lot of assumption is that with the slack in there that the tool is tilting all over the place.
rcoodyar15
07-19-15, 10:08
I wire ejector pin holes with 2 tenths a side clearance and they spin just fine and still have some wobble to them. 4 thou is a bit much. And if the tool is held against one side, in your worst case 4 thou example, the shoulder will still be held square with the face. A lot of assumption is that with the slack in there that the tool is tilting all over the place.
here is an excerpt from the link I supplied. It works for me and others.
Group Therapy
The best time to accurize an AR is while building it, but going back and tweaking an existing rifle or carbine isn’t that difficult. Here again, having a few specialized tools makes the job easier. The two tools I use most often are a receiver lapping tool and muzzle crowning/re-crowning tool set. The lapping tool allows you to “true” the front face of the upper receiver, seating the barrel extension squarely and theoretically aligning the bore with the upper receiver. In this case I’ve found that theory follows practice. I have yet to encounter an AR that hasn’t tightened up noticeably after truing the receiver. In a couple cases this procedure changed 2 MOA plinkers into 3/4 MOA shooters. That’s quite dramatic and makes me wonder where the poor tolerances exist: upper receivers, barrel extensions, barrels or some combination. Care is required to prevent damaging the receiver, as the lapping tool must be well lubricated to prevent “burning” of the inside surfaces of the upper receiver. Commercially available lapping tools have a relief groove to prevent lapping compound from getting inside the upper receiver and removing metal from the wrong places.
rcoodyar15
07-19-15, 10:12
and here is another excerpt from the other link. Success stories are all over. Can we just agree that it works?
I found this thread through a search on the subject. I had a PSA upper that required the rear sight to be moved all the way to the left, to zero the windage. I used this tool and upon checking what it was doing, saw material clearly being removed from one side of the receiver. I continued until the receiver appeared to be the same all the way around, then put my rifle back together. The windage is now correct with the rear sight, dead in the center. I am a believer.
I only wish I had that old Colt H Bar back that I sold 25 years ago, because of this same problem. It went back to Colt but they said there was nothing wrong, so I found it a new home.
There are five dimensions that control the "pinch" of the barrel nut on the barrel extension.
1) the perpendicularity of the pitch diameter of the external threads of the upper to the front face.
2) the perpendicularity of the internal threads of the nut to the seating surface.
3) the variation in thickness of the flange of the barrel extension.
4) the parallelism if the 1.000" bore of the upper to the pitch diameter of the threads.
5) the perpendicularity of the face of the upper to the 1.000" bore of the upper.
Truing the face really only deals with one of these.
As to changing the windage, I have changed the amount of windage required by simply removing and reinstalling the barrel.
Rifle team shooters that I know (including Camp Perry winners) do not have AR's with faced receivers. They all tell me as far as equipment goes, the barrel is the most important. they also tell me even more important is the shooter..... I'm always working on that piece of the equation!
Agreed. I've read a lot on this subject to include input from USMC and USAMU Armorers, former 2112 Marine armorers and high power shooters like Derrick from Acuracy speaks etc. Good barrel, trigger, ammo and someone that can run the gun are the key components. It's all about repeatability and consistency....that is why the Free Float tube made such a big impact in high power. Prior to that slinging up tight could have your point of impact moving around. Even if things are slightly "off" with a receiver face....so long as the rifle is built to spec and stay consistently "off"....it will shoot to the same poa/poi....a BZO - adjusting the sights to the shooter/gun will move those consistent groups into the black.
In the Corps (early 90's) you had to have more than 19 clicks of windage left or right on a BZO before you'd get a mechanical weapons failure and issued a new Rifle for the range. These were on M16A2's...some of which had been re-barreled with the same receivers 6 or 7 times. These weapons were beat to **** and wouldn't pass muster with any civilian armorer, but would still hit man sized targets at 500 with a Devil Dog doing his thing....think about that.
As someone once said. Only accurate guns are interesting....I agree and I'm all for anything that can make a AR more accurate. That said, I don't think some of the tools make much difference other than making someone have a bit more confidence that their build is good to go. Just like the accu-wedge....it makes a shooter feel better that his rifle is "solid"...he may think that it's more accurate (it's not) and he shoots with more confidence because of it. Having confidence in your gear is always a good thing.
elephantrider
07-19-15, 17:26
There are five dimensions that control the "pinch" of the barrel nut on the barrel extension.
1) the perpendicularity of the pitch diameter of the external threads of the upper to the front face.
2) the perpendicularity of the internal threads of the nut to the seating surface.
3) the variation in thickness of the flange of the barrel extension.
4) the parallelism if the 1.000" bore of the upper to the pitch diameter of the threads.
5) the perpendicularity of the face of the upper to the 1.000" bore of the upper.
Truing the face really only deals with one of these.
As to changing the windage, I have changed the amount of windage required by simply removing and reinstalling the barrel.
Please, save your key strokes. This has been explained several times in this thread and he still chooses to breeze past it. Physical measurements and logic are clearly not rcoodyar15's strong suits. Any anecdotal evidence that supports using his magical lapping tool equal absolute proof. Ironically, any incidences of un-lapped rifles that shoot very well with no windage issues are just a one in a thousand fluke. He is a guy who assembled his first AR15 about a year and a half ago, and is now an expert. He has literally bought into this by buying this tool, and seems determined to defend it's validity.
No smart ass, you are reading too deep into my comment. By, all means continue on.
One in a thousand! awesome!
rcoodyar15
07-19-15, 17:52
No smart ass, you are reading too deep into my comment. By, all means continue on.
Just think of what you might have accomplished had you lapped those uppers
rcoodyar15
07-19-15, 18:06
Please, save your key strokes. This has been explained several times in this thread and he still chooses to breeze past it. Physical measurements and logic are clearly not rcoodyar15's strong suits. Any anecdotal evidence that supports using his magical lapping tool equal absolute proof. Ironically, any incidences of un-lapped rifles that shoot very well with no windage issues are just a one in a thousand fluke. He is a guy who assembled his first AR15 about a year and a half ago, and is now an expert. He has literally bought into this by buying this tool, and seems determined to defend it's validity.
hey all I have said is it works for me and seems it works for others too.
Simple tool but then again the AR is a simple rifle. You can put all the tools you need to build one in a grocery sack. It is manufactured with pretty large tolerances where guns can be built from parts from several low bid contractors. Mil spec. is all about keeping all the parts the same from these low bid contractors not about building a better weapon.
I don't care how you are anyone else feels about it. Hell if you don't like it don't use it. But it is really hard for me to understand how someone who has never tried it can be so critical of it.
Comments like this
As to changing the windage, I have changed the amount of windage required by simply removing and reinstalling the barrel.
now theoretically why should removing and reinstalling the barrel change the direction it is pointed?
aren't you curious about that?
need to break out the dial indicators and million dollar milling machine and find out why that worked!
elephantrider
07-19-15, 19:57
hey all I have said is it works for me and seems it works for others too.
Simple tool but then again the AR is a simple rifle. You can put all the tools you need to build one in a grocery sack. It is manufactured with pretty large tolerances where guns can be built from parts from several low bid contractors. Mil spec. is all about keeping all the parts the same from these low bid contractors not about building a better weapon.
I don't care how you are anyone else feels about it. Hell if you don't like it don't use it. But it is really hard for me to understand how someone who has never tried it can be so critical of it.
Comments like this
As to changing the windage, I have changed the amount of windage required by simply removing and reinstalling the barrel.
now theoretically why should removing and reinstalling the barrel change the direction it is pointed?
aren't you curious about that?
need to break out the dial indicators and million dollar milling machine and find out why that worked!
Really? This is getting to AR15.com LULZ levels of derp. Your grasp on "Mil sec," (BTW, I think you mean the TDP, not mil-spec) seems tenuous at best.
You have to stand by the 'don't knock it, til you've tried it,' argument? There are plenty of things that do not need to be tried in order to know that hey either aren't worth it, or are just bad ideas. I'm getting the impression that even if all the necessary measuring equipment were in front of you, you still wouldn't be able to prove or dis-prove what you are talking about.
Comments like this
As to changing the windage, I have changed the amount of windage required by simply removing and reinstalling the barrel.
now theoretically why should removing and reinstalling the barrel change the direction it is pointed?
aren't you curious about that?
Let me answer by asking you a question - if you've torqued a fastener to exactly 35 foot pounds, placed a witness mark, then broken down the assembly and reassembled, if you torque it to exactly 35 foot pounds again, will the witness marks be perfectly aligned? Get it?
As to changing the windage, I have changed the amount of windage required by simply removing and reinstalling the barrel.
now theoretically why should removing and reinstalling the barrel change the direction it is pointed?
aren't you curious about that?
need to break out the dial indicators and million dollar milling machine and find out why that worked!
The slot in the upper for the indexing pin can be a bit wider than the pin itself. The barrel could be reinstalled at a different orientation in the upper, which would affect windage.
rcoodyar15
07-20-15, 07:09
The slot in the upper for the indexing pin can be a bit wider than the pin itself. The barrel could be reinstalled at a different orientation in the upper, which would affect windage.
that doesn't sound very precise.
In other words if you remove and reinstall the barrel it could be, in fact likely to be, pointed in a different direction?
having the mating surface on the front of the receiver square with the part of the upper the bolt carrier rides in and the barrel block that the barrel actually slips into can do nothing to alleviate this?
and you believe that my lapping the front of the receiver can't do anything to help this and is actually going to mess something up.
sounds like to me that it is already messed up.
I think you should do whatever you think is necessary and makes you sleep better. Since the OP has not chimed in and many positions have been presented w can close this for now.
that doesn't sound very precise.
In other words if you remove and reinstall the barrel it could be, in fact likely to be, pointed in a different direction?
having the mating surface on the front of the receiver square with the part of the upper the bolt carrier rides in and the barrel block that the barrel actually slips into can do nothing to alleviate this?
and you believe that my lapping the front of the receiver can't do anything to help this and is actually going to mess something up.
sounds like to me that it is already messed up.
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