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Posted: 6/16/2016 12:43:15 PM EDT
[#1]
I have used bedding compounds to eliminate slop before. Loctite 609 or 620, I can't remember off the top of my head works well for a little slop. You can put several coats of floor wax inside the upper and buff it out. Then apply Devcon epoxy in a very thin coat to the barrel extension when assembling. You will not be taking that upper apart again. Not without undue effort anyway.
The Devcon will fill larger gaps like the one you have. Make sure not to get any inside the upper receiver prior to inserting the barrel extension or it will squish out inside the upper and you will have a hell of a time cleaning it up before it sets. Only apply it to the circumference of the barrel extension. Wipe off everything that seeps out with a rag wet with vinegar. Use plenty of grease on the barrel nut threads. |
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Posted: 6/16/2016 12:50:43 PM EDT
[#2]
Did you ask if they are willing to exchange the upper receiver? I personally would not be happy with that fitment.
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Posted: 6/16/2016 12:56:58 PM EDT
[#3]
Quote HistoryQuoted:
Did you ask if they are willing to exchange the upper receiver? I personally would not be happy with that fitment. I did ask if they would exchange it and they said that it was within their specs...... they told me their spec on the ID is 1.001 +/- .001 .... which is over the spec I have seen on all prints which is .999/1.000. Got a lot of double talk. Yeah, I'm not happy with this at all especially since I thought I purchased a "quality" upper receiver costing twice as much as a "run of the mill" upper receiver. |
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Posted: 6/16/2016 1:44:00 PM EDT
[#4]
Quoted:
I started to assemble a new upper and immediately found that the fit between the barrel/barrel extension and the upper receiver was very loose.... barrel "fell" into the upper with no resistance .... sloppy fit. I measured the barrel extension and found it to be .9981 to .9993.... tapered front to back which is good. I measured the ID of the upper receiver and found it to be 1.001 to 1.002 and out of round by .001. So, from all the specs I can find on an upper receiver, the ID of the upper is oversize. The spec I found on the upper ID is 1.000 max. I called the manufacturer of the upper and they said the upper ID is within spec. I'm kind of bummed out/pissed about this as I purchased a "quality" upper receiver. What do you think? Again, the spec that I have found on the upper receiver ID is .999/1.000. The specified inside diameter for the bore of the upper receiver is 1.000 -0.0/+0.002" Your receiver is within tolerance. (You need to call and apologize) The specified outside diameter diameter of the barrel extension is 0.9987 -.0008/+0.0". Your barrel extension is out tolerance, too large at the big end by 0.0006", and should not be tapered. That's what makes the barrel feel so loose, more clearance in the back allows to front (muzzle) to move more than allowed... I don't know where you got .999" diameter of the upper, but it's wrong. EDIT: And one other thing, at LMC (least material conditions), you are going to have a .0041" clearance between the barrel extension and upper. Yes, that does feel sloppy, but it is per print. |
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Posted: 6/16/2016 2:09:50 PM EDT
[#5]
Is this a competition national match, benchrest, or serious varmint rifle?
Are you using a genuine high end precision barrel? |
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Posted: 6/16/2016 2:39:37 PM EDT
[#6]
Quote HistoryQuoted:
The specified inside diameter for the bore of the upper receiver is 1.000 -0.0/+0.002" Your receiver is within tolerance. (You need to call and apologize) No need to apologize because it was a friendly conversation.... no yelling or complaining .... no problem. The specified outside diameter diameter of the barrel extension is 0.9987 -.0008/+0.0". Your barrel extension is out tolerance, too large at the big end by 0.0006", and should not be tapered. That's what makes the barrel feel so loose, more clearance in the back allows to front (muzzle) to move more than allowed... Well , the barrel is fine even according to the tolerances you have listed because......... .9981 is the diameter at the feed ramps end of the barrel and that is within your spec. It is .9981 for about half the distance then tapers to .9993. What I have read is that a barrel should start in the upper receiver and then get tighter as it is fully seated.... this would mean a slight taper on the extension.... it would start easily and get tighter as it fully seats. This would be ideal. Even according to your listed tolerances, a barrel extension on the low end of tolerance .9979 and an upper receiver on the high end of your tolerance 1.002 would be sloppy ..... my barrel max dia. of .9993 would help tighten things up....... and would work well with a receiver even on the low end of your tolerance ......... 1.000. No argument here .... I'm not arguing with you nor did I argue with the upper manufacturer. My tolerances may be incorrect but I found them in several places: Barrel Ext. tolerance of .9980 to .9995 Upper ID tolerance of .999 to 1.000 Like I said, these dimensions may be wrong. Can you link me to a print or the place where you got your dimensions? Not saying you are wrong ....... just would like to see how the barrel extension and upper are sized and tolerances for each. I just never had this problem before ...... the fits I have experienced in assembling uppers have ranged from snug push in fits to having to warm up the receiver and drawing the barrel down to fully seated with the barrel nut...... never had this problem before or this sloppy of a fit. I don't know where you got .999" diameter of the upper, but it's wrong. It could very well be...... help me out! EDIT: And one other thing, at LMC (least material conditions), you are going to have a .0041" clearance between the barrel extension and upper. Yes, that does feel sloppy, but it is per print. I understand. Quote HistoryQuoted:
Quoted:
I started to assemble a new upper and immediately found that the fit between the barrel/barrel extension and the upper receiver was very loose.... barrel "fell" into the upper with no resistance .... sloppy fit. I measured the barrel extension and found it to be .9981 to .9993.... tapered front to back which is good. I measured the ID of the upper receiver and found it to be 1.001 to 1.002 and out of round by .001. So, from all the specs I can find on an upper receiver, the ID of the upper is oversize. The spec I found on the upper ID is 1.000 max. I called the manufacturer of the upper and they said the upper ID is within spec. I'm kind of bummed out/pissed about this as I purchased a "quality" upper receiver. What do you think? Again, the spec that I have found on the upper receiver ID is .999/1.000. The specified inside diameter for the bore of the upper receiver is 1.000 -0.0/+0.002" Your receiver is within tolerance. (You need to call and apologize) No need to apologize because it was a friendly conversation.... no yelling or complaining .... no problem. The specified outside diameter diameter of the barrel extension is 0.9987 -.0008/+0.0". Your barrel extension is out tolerance, too large at the big end by 0.0006", and should not be tapered. That's what makes the barrel feel so loose, more clearance in the back allows to front (muzzle) to move more than allowed... Well , the barrel is fine even according to the tolerances you have listed because......... .9981 is the diameter at the feed ramps end of the barrel and that is within your spec. It is .9981 for about half the distance then tapers to .9993. What I have read is that a barrel should start in the upper receiver and then get tighter as it is fully seated.... this would mean a slight taper on the extension.... it would start easily and get tighter as it fully seats. This would be ideal. Even according to your listed tolerances, a barrel extension on the low end of tolerance .9979 and an upper receiver on the high end of your tolerance 1.002 would be sloppy ..... my barrel max dia. of .9993 would help tighten things up....... and would work well with a receiver even on the low end of your tolerance ......... 1.000. No argument here .... I'm not arguing with you nor did I argue with the upper manufacturer. My tolerances may be incorrect but I found them in several places: Barrel Ext. tolerance of .9980 to .9995 Upper ID tolerance of .999 to 1.000 Like I said, these dimensions may be wrong. Can you link me to a print or the place where you got your dimensions? Not saying you are wrong ....... just would like to see how the barrel extension and upper are sized and tolerances for each. I just never had this problem before ...... the fits I have experienced in assembling uppers have ranged from snug push in fits to having to warm up the receiver and drawing the barrel down to fully seated with the barrel nut...... never had this problem before or this sloppy of a fit. I don't know where you got .999" diameter of the upper, but it's wrong. It could very well be...... help me out! EDIT: And one other thing, at LMC (least material conditions), you are going to have a .0041" clearance between the barrel extension and upper. Yes, that does feel sloppy, but it is per print. I understand. ETA: Also consider the fact that this is a high dollar upper receiver known for close tolerances , face squareness etc. I have used them before and never had a problem. If this was a " run of the mill" receiver I wouldn't even have raised a question. |
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Posted: 6/16/2016 2:46:27 PM EDT
[#7]
Install the barrel, torque to the require torque spec and forget it. The clamping loads are enormous (over 10,000 lbs at 40 Ft-Lbs of barrel nut torque) The barrel is not going to move once its installed.
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Posted: 6/16/2016 2:52:58 PM EDT
[#8]
Quote HistoryQuoted:
Install the barrel, torque to the require torque spec and forget it. The clamping loads are enormous (over 10,000 lbs at 40 Ft-Lbs of barrel nut torque) The barrel is not going to move once its installed. True but barrel movement after installation is not my concern. |
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Posted: 6/16/2016 3:03:19 PM EDT
[#9]
Quote HistoryQuoted:
[span style='color: blue;']Well , the barrel is fine even according to the tolerances you have listed because......... .9981 is the diameter at the feed ramps end of the barrel and that is within your spec. It is .9981 for about half the distance then tapers to .9993. What I have read is that a barrel should start in the upper receiver and then get tighter as it is fully seated.... this would mean a slight taper on the extension.... it would start easily and get tighter as it fully seats. This would be ideal. Even according to your listed tolerances, a barrel extension on the low end of tolerance .9979 and an upper receiver on the high end of your tolerance 1.002 would be sloppy ..... my barrel max dia. of .9993 would help tighten things up....... and would work well with a receiver even on the low end of your tolerance ......... 1.000. You are reading the tolerances wrong. The acceptable diameter for the barrel extension are .9987 plus zero/minus .0008". That means the maximum diameter you should ever have is 0.9987", the minimum diameter is .9979". Yours is outside that .9979 to .9987 range, by .0006". (Not that it make a piece of difference, as long as the two parts slip together without any force.) These two parts are not supposed to be a force or interference fit. The tolerancing is for an ANSI locational slip fit, with a class 6 fit. BTW, the perpendicularity of the flange on the extension and the face of the upper to the bore centerline are more important than the diameters..... |
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Posted: 6/16/2016 3:03:58 PM EDT
[#10]
Quote HistoryQuoted:
True but barrel movement after installation is not my concern. Quote HistoryQuoted:
Quoted:
Install the barrel, torque to the require torque spec and forget it. The clamping loads are enormous (over 10,000 lbs at 40 Ft-Lbs of barrel nut torque) The barrel is not going to move once its installed. True but barrel movement after installation is not my concern. You torque it to 40 ft-lbs, it ain't moving.... |
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Posted: 6/16/2016 3:29:40 PM EDT
[#11]
Quote HistoryQuoted:
You are reading the tolerances wrong. The acceptable diameter for the barrel extension are .9987 plus zero/minus .0008". That means the maximum diameter you should ever have is 0.9987", the minimum diameter is .9979". Yours is outside that .9979 to .9987 range, by .0006". No, I read the tolerance correctly....... I said low end of tolerance at .9979...... I understand the tolerance is .9979 to .9987. Also, my barrel extensions max dia. of .9993 would easily fit an upper receiver with the minimum dia of 1.000. So, what I am saying is that even though my barrel extension may be oversize to the tolerances you have listed, it would STILL fit an upper receiver that was at the exact low end of your tolerances...... that would be 1.000. A barrel extension measuring .9993 would fit in the 1.000 minimum dia. upper no problem. (Not that it make a piece of difference, as long as the two parts slip together without any force.) These two parts are not supposed to be a force or interference fit. The tolerancing is for an ANSI locational slip fit, with a class 6 fit. Actually the tighter the better ....... within reason of course. Having to warm up the upper receiver a little with a hair dryer and LIGHTLY tapping the barrel in is ideal..... from an accuracy standpoint. BTW, the perpendicularity of the flange on the extension and the face of the upper to the bore centerline are more important than the diameters..... [span style='color: blue;']I would agree. Quote HistoryQuoted:
Quoted:
Well , the barrel is fine even according to the tolerances you have listed because......... .9981 is the diameter at the feed ramps end of the barrel and that is within your spec. It is .9981 for about half the distance then tapers to .9993. What I have read is that a barrel should start in the upper receiver and then get tighter as it is fully seated.... this would mean a slight taper on the extension.... it would start easily and get tighter as it fully seats. This would be ideal. Even according to your listed tolerances, a barrel extension on the low end of tolerance .9979 and an upper receiver on the high end of your tolerance 1.002 would be sloppy ..... my barrel max dia. of .9993 would help tighten things up....... and would work well with a receiver even on the low end of your tolerance ......... 1.000. You are reading the tolerances wrong. The acceptable diameter for the barrel extension are .9987 plus zero/minus .0008". That means the maximum diameter you should ever have is 0.9987", the minimum diameter is .9979". Yours is outside that .9979 to .9987 range, by .0006". No, I read the tolerance correctly....... I said low end of tolerance at .9979...... I understand the tolerance is .9979 to .9987. Also, my barrel extensions max dia. of .9993 would easily fit an upper receiver with the minimum dia of 1.000. So, what I am saying is that even though my barrel extension may be oversize to the tolerances you have listed, it would STILL fit an upper receiver that was at the exact low end of your tolerances...... that would be 1.000. A barrel extension measuring .9993 would fit in the 1.000 minimum dia. upper no problem. (Not that it make a piece of difference, as long as the two parts slip together without any force.) These two parts are not supposed to be a force or interference fit. The tolerancing is for an ANSI locational slip fit, with a class 6 fit. Actually the tighter the better ....... within reason of course. Having to warm up the upper receiver a little with a hair dryer and LIGHTLY tapping the barrel in is ideal..... from an accuracy standpoint. BTW, the perpendicularity of the flange on the extension and the face of the upper to the bore centerline are more important than the diameters..... [span style='color: blue;']I would agree. Again, I am talking about an upper that is said to be close tolerance, high quality........ ETA: and you were correct........ I found a print and the upper diameter is listed at 1.0000 +.002/-.000 I am very surprised that much slop is spec'ed in this fit. |
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Posted: 6/16/2016 3:44:26 PM EDT
[#12]
I'd wipe the barrel extension down with a thin layer of blue loctite, assemble, and torque down the barrel nut. It acts like a bedding compound and should take care of an concerns you have.
BTW: you can use red loctite instead of Blue, but it will be much more difficult to break free. |
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Posted: 6/16/2016 6:34:12 PM EDT
[#13]
Competition shooters use .001" or .002" steel shim stock and wrap in around the barrel extension to take up the slack and tap the barrel into place. If that shim stock is too thick I'd say that you really don't have a problem and torqueing the barrel nut to spec is all you need.
Here is a link. Scroll down a bit and see procedure and photo. http://www.ar15.com/forums/t_16_4/42_Hellbenders_guides_to_Ultimate_AR15_and_or_AR10.html |
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Posted: 6/16/2016 8:03:43 PM EDT
[#14]
Soda / Beer cans seem to run from .003 to .005. You now have a reason to drink one and test the fit.
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Posted: 6/17/2016 7:08:51 AM EDT
[#15]
OP
Replace the receiver if it is that important yo you. Order a BCM stripped receiver. They are very tight on tolerances |
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Posted: 6/17/2016 8:53:23 AM EDT
[#16]
Quote HistoryQuoted:
OP Replace the receiver if it is that important yo you. Order a BCM stripped receiver. They are very tight on tolerances That's no joke. Just installed a barrel in a stripped bcm upper. The barrel extension removed anodizing from the receiver as I was pushing it in. My preference is for Mega Arms. Tight and smooth, no need to break out a wooden mallet. |
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Posted: 6/20/2016 8:31:13 AM EDT
[#17]
Quote HistoryQuoted:
That's no joke. Just installed a barrel in a stripped bcm upper. The barrel extension removed anodizing from the receiver as I was pushing it in. My preference is for Mega Arms. Tight and smooth, no need to break out a wooden mallet. Quote HistoryQuoted:
Quoted:
OP Replace the receiver if it is that important yo you. Order a BCM stripped receiver. They are very tight on tolerances That's no joke. Just installed a barrel in a stripped bcm upper. The barrel extension removed anodizing from the receiver as I was pushing it in. My preference is for Mega Arms. Tight and smooth, no need to break out a wooden mallet. A few minutes with a heat gun was all I needed to install the barrel. |
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