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Posted: 4/29/2016 5:24:24 PM EDT
[#1]
I've bedded with green Loctite in the past. I will probably do one next week with blue Loctite as I'm waiting on a Krieger barrel that will probably replace the Criterion that's arriving Monday. Several people have recommended blue Loctite in other threads.
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Posted: 4/29/2016 5:30:59 PM EDT
[#2]
Quote HistoryQuoted:
I've bedded with green Loctite in the past. I will probably do one next week with blue Loctite as I'm waiting on a Krieger barrel that will probably replace the Criterion that's arriving Monday. Several people have recommended blue Loctite in other threads. Thanks. Putting a Criterion in myself. |
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Posted: 4/29/2016 5:32:50 PM EDT
[#3]
Quote HistoryQuoted:
I've bedded with green Loctite in the past. I will probably do one next week with blue Loctite as I'm waiting on a Krieger barrel that will probably replace the Criterion that's arriving Monday. Several people have recommended blue Loctite in other threads. I was gonna say blue. You gotta be real generous with it, and clean the fuck out if your extension once your done and it's set. Not sure what others do, but i crank down on the barrel nut to about 40 or so lbs, let it set. Then come back and attempt to goto 60lbs. I really like these handguards that don't need a timed barrel nut. Makes that part of the job easier. I used brake cleaner to strip both the barrel and upper first. |
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Posted: 4/29/2016 5:34:06 PM EDT
[#4]
My Ballistic Advantage barrel's extension measured 1.186" and was a bit wobbly in my Aero Precision M5E1 upper. Read everything I could find on bedding and seeing every recommendation under the sun I decided to just try out some Vibra-Tite 121 (?, maybe 122) since I had some around. It's supposed to be equivalent to standard blue Loctite. Don't know if I needed it or if it helped but I do know it's shooting under MOA. I'll know more when the barrel is shot out or if accuracy degrades prematurely and I remove it.
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Posted: 4/29/2016 6:04:07 PM EDT
[#5]
Curios if anyone has tried acraglass ?
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Posted: 4/29/2016 7:22:51 PM EDT
[#6]
On my .22-250 upper, nothing. The BAT machine extension fit the Armalite upper receiver with about .0005 clearance. Shoots in the .3's.
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Posted: 4/29/2016 7:27:30 PM EDT
[#7]
Quote HistoryQuoted: On my .22-250 upper, nothing. The BAT machine extension fit the Armalite upper receiver with about .0005 clearance. Shoots in the .3's. |
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Posted: 4/29/2016 7:46:43 PM EDT
[#8]
Look at 609 and 620, they both are designed for cylindrical slip fit parts and hold up well under high heat.
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Posted: 4/29/2016 9:02:12 PM EDT
[#9]
I cerakote the extension and then polish to fit.
KEY: polish to a SMOOTH FIT NOT A TIGHT FIT. The minute you feel resistance.....stop, and polish where the tightness begins...OR YOU WILL SEIZE THE EXTENSION TO THE UPPER. |
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Posted: 4/29/2016 9:04:48 PM EDT
[#10]
Quote HistoryQuoted: Look at 609 and 620, they both are designed for cylindrical slip fit parts and hold up well under high heat. |
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Posted: 4/29/2016 9:08:28 PM EDT
[#11]
Wait, you're loctating the barrel into the receiver?
For an AR10?! |
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Posted: 4/29/2016 9:43:51 PM EDT
[#12]
Quote HistoryQuoted: Wait, you're loctating the barrel into the receiver? For an AR10?! |
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Posted: 4/29/2016 9:50:16 PM EDT
[#13]
Quote HistoryQuoted:
Wait, you're loctating the barrel into the receiver? For an AR10?! Just to clarify: The barrel extension is bedded into the upper receiver. The barrel nut to upper is NOT loctited Greased and torqued as normal. |
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Posted: 4/29/2016 10:29:24 PM EDT
[#14]
Quote HistoryQuoted: Yes. Quote HistoryQuoted: Quoted: Wait, you're loctating the barrel into the receiver? For an AR10?! Yup Yup....sometimes AR-10 extensions and recievers can be a bit on the loose side so a lot of folks shim or bed or loc tite them into place. I shim with CeraKote. I don't think there is necessarily a best or better method, they all seem to work well. |
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Posted: 4/29/2016 11:46:29 PM EDT
[#15]
Quote HistoryQuoted:
Just to clarify: The barrel extension is bedded into the upper receiver. The barrel nut to upper is NOT loctited Greased and torqued as normal. Quote HistoryQuoted:
Quoted:
Wait, you're loctating the barrel into the receiver? For an AR10?! Just to clarify: The barrel extension is bedded into the upper receiver. The barrel nut to upper is NOT loctited Greased and torqued as normal. I have two hypotheses: 1) Not a single reputable manufacturer of AR platform rifles "beds" their rifles with chemical adhesives like this. 2) No evidence exists that demonstrates this enhances accuracy or serves any benefit, in any way. Now, I'm not saying that doing this is ludicrous, but only that after having worked for multiple AR manufacturers I've not observed anything that supports that this is a good idea in any way. Is this something done in the .308 world? |
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Posted: 4/30/2016 12:21:13 AM EDT
[#16]
Quote HistoryQuoted:
I cerakote the extension and then polish to fit. KEY: polish to a SMOOTH FIT NOT A TIGHT FIT. The minute you feel resistance.....stop, and polish where the tightness begins...OR YOU WILL SEIZE THE EXTENSION TO THE UPPER. I Cerakote the inside of the upper where the extension tunnel is. Then press-fit with Blue Loc-tite. You will not seize the barrel in the upper, and they are rather easy to remove with a tap on a Delrin insert. Some manufacturers use an interference thermal fit, where there is no way to get them apart without heating after freezing. |
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Posted: 4/30/2016 12:28:56 AM EDT
[#17]
Quote HistoryQuoted:
I have two hypotheses: 1) Not a single reputable manufacturer of AR platform rifles "beds" their rifles with chemical adhesives like this. 2) No evidence exists that demonstrates this enhances accuracy or serves any benefit, in any way. Now, I'm not saying that doing this is ludicrous, but only that after having worked for multiple AR manufacturers I've not observed anything that supports that this is a good idea in any way. Is this something done in the .308 world? Quote HistoryQuoted:
Quoted:
Quoted:
Wait, you're loctating the barrel into the receiver? For an AR10?! Just to clarify: The barrel extension is bedded into the upper receiver. The barrel nut to upper is NOT loctited Greased and torqued as normal. I have two hypotheses: 1) Not a single reputable manufacturer of AR platform rifles "beds" their rifles with chemical adhesives like this. 2) No evidence exists that demonstrates this enhances accuracy or serves any benefit, in any way. Now, I'm not saying that doing this is ludicrous, but only that after having worked for multiple AR manufacturers I've not observed anything that supports that this is a good idea in any way. Is this something done in the .308 world? Just because the manufacturers you worked with didn't do it, doesn't mean there aren't reputable manufacturers doing it. I've seen it tighten-up groups on sloppy-fit extension-to-upper interface on several guns, both AR10 and AR15. There are other ways of skinning the cat from a manufacturing perspective, like specifying undersized extension tunnels in your uppers, and maximum spec ODs on your extensions. I know reputable manufacturers who do both interference fit and Blue Loc-tite to bed. I do it on all my precision builds. Maybe I'm just doing it wrong though. This 6rd + group was fired at 1000yds rapid, from an extremely lightweight Lilja Wasp profile 6.5 Grendel barrel. The whole rifle with optics weighs 7lbs 12 oz. empty. It's boring to shoot at closer distances unless you get on a shot timer and see how fast you can transition target-to-target. 
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Posted: 4/30/2016 12:32:25 AM EDT
[#18]
Quote HistoryQuoted:
I have two hypotheses: 1) Not a single reputable manufacturer of AR platform rifles "beds" their rifles with chemical adhesives like this. 2) No evidence exists that demonstrates this enhances accuracy or serves any benefit, in any way. Now, I'm not saying that doing this is ludicrous, but only that after having worked for multiple AR manufacturers I've not observed anything that supports that this is a good idea in any way. Is this something done in the .308 world? Quote HistoryQuoted:
Quoted:
Quoted:
Wait, you're loctating the barrel into the receiver? For an AR10?! Just to clarify: The barrel extension is bedded into the upper receiver. The barrel nut to upper is NOT loctited Greased and torqued as normal. I have two hypotheses: 1) Not a single reputable manufacturer of AR platform rifles "beds" their rifles with chemical adhesives like this. 2) No evidence exists that demonstrates this enhances accuracy or serves any benefit, in any way. Now, I'm not saying that doing this is ludicrous, but only that after having worked for multiple AR manufacturers I've not observed anything that supports that this is a good idea in any way. Is this something done in the .308 world? It's done in both the .308 and AR15 world. Most precision builders will do it. They use loctite, rocksett, shims, or oversize barrel extensions turned down to fit. |
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Posted: 4/30/2016 2:00:41 AM EDT
[#19]
Quote HistoryQuoted:
Just because the manufacturers you worked with didn't do it, doesn't mean there aren't reputable manufacturers doing it. I've seen it tighten-up groups on sloppy-fit extension-to-upper interface on several guns, both AR10 and AR15. There are other ways of skinning the cat from a manufacturing perspective, like specifying undersized extension tunnels in your uppers, and maximum spec ODs on your extensions. I know reputable manufacturers who do both interference fit and Blue Loc-tite to bed. I do it on all my precision builds. Maybe I'm just doing it wrong though. This 6rd + group was fired at 1000yds rapid, from an extremely lightweight Lilja Wasp profile 6.5 Grendel barrel. The whole rifle with optics weighs 7lbs 12 oz. empty. It's boring to shoot at closer distances unless you get on a shot timer and see how fast you can transition target-to-target. http://i1085.photobucket.com/albums/j422/LRRPF52/3bf6ee00-ad92-4600-a7bb-e77b0832f99f_zpsfe8pbfh3.jpg http://i1085.photobucket.com/albums/j422/LRRPF52/IMG_04191_zpsqlixp3o5.jpg Quote HistoryQuoted:
Just because the manufacturers you worked with didn't do it, doesn't mean there aren't reputable manufacturers doing it. I've seen it tighten-up groups on sloppy-fit extension-to-upper interface on several guns, both AR10 and AR15. There are other ways of skinning the cat from a manufacturing perspective, like specifying undersized extension tunnels in your uppers, and maximum spec ODs on your extensions. I know reputable manufacturers who do both interference fit and Blue Loc-tite to bed. I do it on all my precision builds. Maybe I'm just doing it wrong though. This 6rd + group was fired at 1000yds rapid, from an extremely lightweight Lilja Wasp profile 6.5 Grendel barrel. The whole rifle with optics weighs 7lbs 12 oz. empty. It's boring to shoot at closer distances unless you get on a shot timer and see how fast you can transition target-to-target. http://i1085.photobucket.com/albums/j422/LRRPF52/3bf6ee00-ad92-4600-a7bb-e77b0832f99f_zpsfe8pbfh3.jpg http://i1085.photobucket.com/albums/j422/LRRPF52/IMG_04191_zpsqlixp3o5.jpg Just to be clear, you assembled rifles, shot them, tore them down and reinstalled the barrel, and shot them again? What kind of improvement did you see? Not doubting you, just genuinely curious as to the results. Quoted:
It's done in both the .308 and AR15 world. Most precision builders will do it. They use loctite, rocksett, shims, or oversize barrel extensions turned down to fit. Done by whom? I don't know of a single one that does. Most builders & manufacturers like KAC, Noveske, Armalite, DPMS, Mega, Alexander, LWRC, POF, BM, BCM, Vltor, Rainer, and others do not. That's not to say it's not possible, but it does seem like if it was a cheap, easy, and verifiable boost to accuracy, more companies would be doing it. |
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Posted: 4/30/2016 6:02:59 AM EDT
[#20]
Quote HistoryQuoted:
Done by whom? I don't know of a single one that does. Most builders & manufacturers like KAC, Noveske, Armalite, DPMS, Mega, Alexander, LWRC, POF, BM, BCM, Vltor, Rainer, and others do not. That's not to say it's not possible, but it does seem like if it was a cheap, easy, and verifiable boost to accuracy, more companies would be doing it. Not one of those companies you listed is a precision builder. Although I'm sure some of them are specing much tighter tolerances to accomplish the same thing. Go to a competition where scores are measured by the thousandth of an inch and you'll see the guys that are doing this kind of thing. I don't really follow that world anymore, but I'd guess that with the current state of the AR aftermarket, most of them are probably using oversized barrel extensions and undersized receiver bores these days instead of bedding compounds and shim stock. But seeing red loctite smeared on the barrel extensions and even gas blocks was a common sight back in the 90s and early 2000s. |
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Posted: 4/30/2016 7:14:22 AM EDT
[#21]
Quote HistoryQuoted:
Isn't BAT known for making slightly oversize extensions? Really comes in handy for accuracy builds. Quote HistoryQuoted:
Quoted:
On my .22-250 upper, nothing. The BAT machine extension fit the Armalite upper receiver with about .0005 clearance. Shoots in the .3's. That would explain why the BHW barrels fit so well into my uppers. They use BAT. 
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Posted: 4/30/2016 9:02:49 AM EDT
[#22]
Loctite isn't a bedding compound. It only cures in the absence of oxygen.
I have serious doubts about the benifits of bedding an extension as most bedding compounds are at least slightly compressible and the amount you could get between the receiver and extension would be negligible. Plus, most melt at high temps. If you truly wanted to unitize the parts, a high temp glue would be superior. |
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Posted: 4/30/2016 10:50:20 AM EDT
[#23]
Quote HistoryQuoted:
Just to be clear, you assembled rifles, shot them, tore them down and reinstalled the barrel, and shot them again? What kind of improvement did you see? Not doubting you, just genuinely curious as to the results. Done by whom? I don't know of a single one that does. Most builders & manufacturers like KAC, Noveske, Armalite, DPMS, Mega, Alexander, LWRC, POF, BM, BCM, Vltor, Rainer, and others do not. That's not to say it's not possible, but it does seem like if it was a cheap, easy, and verifiable boost to accuracy, more companies would be doing it. Quote HistoryQuoted:
Quoted:
Just because the manufacturers you worked with didn't do it, doesn't mean there aren't reputable manufacturers doing it. I've seen it tighten-up groups on sloppy-fit extension-to-upper interface on several guns, both AR10 and AR15. There are other ways of skinning the cat from a manufacturing perspective, like specifying undersized extension tunnels in your uppers, and maximum spec ODs on your extensions. I know reputable manufacturers who do both interference fit and Blue Loc-tite to bed. I do it on all my precision builds. Maybe I'm just doing it wrong though. This 6rd + group was fired at 1000yds rapid, from an extremely lightweight Lilja Wasp profile 6.5 Grendel barrel. The whole rifle with optics weighs 7lbs 12 oz. empty. It's boring to shoot at closer distances unless you get on a shot timer and see how fast you can transition target-to-target. http://i1085.photobucket.com/albums/j422/LRRPF52/3bf6ee00-ad92-4600-a7bb-e77b0832f99f_zpsfe8pbfh3.jpg http://i1085.photobucket.com/albums/j422/LRRPF52/IMG_04191_zpsqlixp3o5.jpg Just to be clear, you assembled rifles, shot them, tore them down and reinstalled the barrel, and shot them again? What kind of improvement did you see? Not doubting you, just genuinely curious as to the results. Quoted:
It's done in both the .308 and AR15 world. Most precision builders will do it. They use loctite, rocksett, shims, or oversize barrel extensions turned down to fit. Done by whom? I don't know of a single one that does. Most builders & manufacturers like KAC, Noveske, Armalite, DPMS, Mega, Alexander, LWRC, POF, BM, BCM, Vltor, Rainer, and others do not. That's not to say it's not possible, but it does seem like if it was a cheap, easy, and verifiable boost to accuracy, more companies would be doing it. I will personally test this if you like. I am a shooter as a hobby, but am pretty good. I have a Creedmoor build that will be done soon, I will put it together without bedding, shoot it till broke in , (say 200rds) and then break it down and re do with bedding. Problem is its a new barrel and ya know how that goes. You send me 120 rds of the ammo it ends up liking best after getting broke in and I will give you an honest side by side comparison. How about 3x10 shot groups at 200yds for each barrel setup. I will give you the best comparison I can, shooting will be done prone, with bipod and 16x scope. Anything you can think of to keep it more scientific, I will attempt to do, but variables happen. Barrel is a Criterion and upper is an Aero 308 M5, both are new and fit is a bit loose in my opinoin. |
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Posted: 4/30/2016 11:00:16 AM EDT
[#24]
Aero M5 with a Fulton Armory finished Criterion barrel is the same setup I'll be assembling next week.
I'm not sure how much good bedding the barrel to the receiver does, but it's easy and it might help. |
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Posted: 4/30/2016 11:14:42 AM EDT
[#25]
You can buy rolls of 0.001" stainless steel shim stock and cut out strips to wrap around the barrel extension before sliding it in. If you are patient and careful, you can get it very tight without crimping the shim material.
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Posted: 4/30/2016 11:23:51 AM EDT
[#26]
Quote HistoryQuoted:
Aero M5 with a Fulton Armory finished Criterion barrel is the same setup I'll be assembling next week. I'm not sure how much good bedding the barrel to the receiver does, but it's easy and it might help. Thats my setup as well. I'm gonna lap and bed. But this thread has got me thinking about trying a before and after. 1. Assemble as normal. 2. Assemble after lapping 3. Assemble after bedding ?? Might waste some ammo with this. |
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Posted: 4/30/2016 11:51:04 AM EDT
[#27]
Quote HistoryQuoted:
Just to be clear, you assembled rifles, shot them, tore them down and reinstalled the barrel, and shot them again? What kind of improvement did you see? Not doubting you, just genuinely curious as to the results. Done by whom? I don't know of a single one that does. Most builders & manufacturers like KAC, Noveske, Armalite, DPMS, Mega, Alexander, LWRC, POF, BM, BCM, Vltor, Rainer, and others do not. That's not to say it's not possible, but it does seem like if it was a cheap, easy, and verifiable boost to accuracy, more companies would be doing it. Quote HistoryQuoted:
Quoted:
Just because the manufacturers you worked with didn't do it, doesn't mean there aren't reputable manufacturers doing it. I've seen it tighten-up groups on sloppy-fit extension-to-upper interface on several guns, both AR10 and AR15. There are other ways of skinning the cat from a manufacturing perspective, like specifying undersized extension tunnels in your uppers, and maximum spec ODs on your extensions. I know reputable manufacturers who do both interference fit and Blue Loc-tite to bed. I do it on all my precision builds. Maybe I'm just doing it wrong though. This 6rd + group was fired at 1000yds rapid, from an extremely lightweight Lilja Wasp profile 6.5 Grendel barrel. The whole rifle with optics weighs 7lbs 12 oz. empty. It's boring to shoot at closer distances unless you get on a shot timer and see how fast you can transition target-to-target. http://i1085.photobucket.com/albums/j422/LRRPF52/3bf6ee00-ad92-4600-a7bb-e77b0832f99f_zpsfe8pbfh3.jpg http://i1085.photobucket.com/albums/j422/LRRPF52/IMG_04191_zpsqlixp3o5.jpg Just to be clear, you assembled rifles, shot them, tore them down and reinstalled the barrel, and shot them again? What kind of improvement did you see? Not doubting you, just genuinely curious as to the results. Quoted:
It's done in both the .308 and AR15 world. Most precision builders will do it. They use loctite, rocksett, shims, or oversize barrel extensions turned down to fit. Done by whom? I don't know of a single one that does. Most builders & manufacturers like KAC, Noveske, Armalite, DPMS, Mega, Alexander, LWRC, POF, BM, BCM, Vltor, Rainer, and others do not. That's not to say it's not possible, but it does seem like if it was a cheap, easy, and verifiable boost to accuracy, more companies would be doing it. I first saw this with a JP barreled build I did. Couldn't get much better than 1.7" at 100yds consistently with it, and I suspected the barrel was capable of much better than that. I pulled it, lapped the receiver face, Cerakoted the upper, including the extension tunnel, and bedded the barrel with Blue Loc tite. Now it bug holes even with cheap 55gr in a new shooter's hands. Also, I re-built a friend's IRA .308 with Krieger barrel. Before, it was shooting 1.5" at best. After, it now shoots in the .6s with a random hand load, 5rd groups. Alexander Arms beds 20" and longer uppers. I've disassembled them. Ask anyone about trying to get a BCM upper apart. Les Baer does as well. GA Precision does. I've had them build 2 LRs for me, one in .308, the other in .260 Remington. Companies that are known for extreme accuracy do. Most of the companies you listed are mass-producers, not known for precision guns. |
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Posted: 4/30/2016 4:58:44 PM EDT
[#28]
I have yet to see any documented evidence - with before/after comparisons to show the difference - that "bedding" an AR barrel in the upper has any affect on accuracy, assuming we're talking about quality uppers and barrels, I can't see any mechanism, once a barrel is properly installed, that could lead to decreased accuracy if the extension wasn't a really snug fit in the upper.
With that said, I know competitive swimmers who freely admit that shaving every single hair from their bodies can't possibly make them faster in the water, but they will say "I feel slicker, so that makes me feel faster." If you want to ensure a snug fit between the barrel extension and the upper, feel free to do whatever to get the snugness you want. I'd suggest using stainless shim tape, or aluminum tape. I don't know how hot an AR barrel gets right outside the chamber, but I'm thinking it can exceed the failure temperature of most thread locking compounds. Loctite 294, High Temperature Threadlocker (Green) is rated to work up to 450ºF, as is 620. 609 is only rated to 300ºF. That would not give me a lot of confidence that the stuff would maintain the parts aligned the way I wanted. |
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Posted: 4/30/2016 5:09:16 PM EDT
[#29]
I just don't think heat is a huge issue on these accuracy builds we are bedding. Almost everyone bedding a barrel is using a fairly heavy profile and we aren't doing mag dumps with them. A couple mag dumps at full auto rates. would start eating the throat and cutting our accuracy potential.
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Posted: 4/30/2016 5:13:37 PM EDT
[#30]
Quote HistoryQuoted:
I just don't think heat is a huge issue on these accuracy builds we are bedding. Almost everyone bedding a barrel is using a fairly heavy profile and we aren't doing mag dumps with them. A couple mag dumps at full auto rates. would start eating the throat and cutting our accuracy potential. Good point. Really precision shooting doesn't get barrels terribly warm. On the other hand, I think of it like this: any liquid is going to go where it wants to, while a shim (or tape) stays where you put it. If I were going for as close to perfectly centered in the upper, I'd go with stainless shim tape to ensure that concentricity was as precise as possible. |
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Posted: 4/30/2016 5:40:50 PM EDT
[#31]
You can shim, thermo-fit, spec out interference fit parts, and some do combinations of these.
A reputable precision rifle shop isn't just throwing the barrel in and torquing it, then calling it good. Higher torque is another approach with the barrel nut. If you look at the AMU and where this originated when a guy saw flex in his extension as he moved the barrel at a match down in Australia back when they had A1s, you can learn more about where it originated. There was a good video posted not too long ago where this was all detailed. I know guys that do precision work who have been doing it for almost 20 years. They've even tried JB Weld, glass bedding, you name it. One in particular doesn't have to advertise, and has done a lot of work for people in a certain unit in the Fort Bragg area, and continues to do work for guys from there on their personal guns. He's an artisan with black rifles, not just an assembler. He currently sources under-sized uppers and over-sized extensions for precision builds, and still uses Loc-tite. The problem I see with this is a lot of novices jumping in and incorporating this into their normal assembly procedure, especially on their first guns, where they spent $100 on a garbage barrel from Jim Bo's Tactical Start-Ups, with a chamber that is below minimum spec, they don't quite get the concept of gas block alignment with the ports, and then expect sub-MOA performance. |
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Posted: 4/30/2016 7:38:36 PM EDT
[#32]
Quote HistoryQuoted: You can shim, thermo-fit, spec out interference fit parts, and some do combinations of these. A reputable precision rifle shop isn't just throwing the barrel in and torquing it, then calling it good. Higher torque is another approach with the barrel nut. If you look at the AMU and where this originated when a guy saw flex in his extension as he moved the barrel at a match down in Australia back when they had A1s, you can learn more about where it originated. There was a good video posted not too long ago where this was all detailed. I know guys that do precision work who have been doing it for almost 20 years. They've even tried JB Weld, glass bedding, you name it. One in particular doesn't have to advertise, and has done a lot of work for people in a certain unit in the Fort Bragg area, and continues to do work for guys from there on their personal guns. He's an artisan with black rifles, not just an assembler. He currently sources under-sized uppers and over-sized extensions for precision builds, and still uses Loc-tite. The problem I see with this is a lot of novices jumping in and incorporating this into their normal assembly procedure, especially on their first guns, where they spent $100 on a garbage barrel from Jim Bo's Tactical Start-Ups, with a chamber that is below minimum spec, they don't quite get the concept of gas block alignment with the ports, and then expect sub-MOA performance. Well said! $15.99 is NOT gonna buy you $3000.00 in performance. Shit, even spending a lot of dough on a full setup can give you headaches. Anyone remember my Wilson gas tube/gas block issue on my Mega? 'Cuz I am still trying to forget it. |
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Posted: 5/1/2016 10:54:15 AM EDT
[#33]
Quote HistoryQuoted:
Well said! $15.99 is NOT gonna buy you $3000.00 in performance. Shit, even spending a lot of dough on a full setup can give you headaches. Anyone remember my Wilson gas tube/gas block issue on my Mega? 'Cuz I am still trying to forget it. Quote HistoryQuoted:
Quoted:
You can shim, thermo-fit, spec out interference fit parts, and some do combinations of these. A reputable precision rifle shop isn't just throwing the barrel in and torquing it, then calling it good. Higher torque is another approach with the barrel nut. If you look at the AMU and where this originated when a guy saw flex in his extension as he moved the barrel at a match down in Australia back when they had A1s, you can learn more about where it originated. There was a good video posted not too long ago where this was all detailed. I know guys that do precision work who have been doing it for almost 20 years. They've even tried JB Weld, glass bedding, you name it. One in particular doesn't have to advertise, and has done a lot of work for people in a certain unit in the Fort Bragg area, and continues to do work for guys from there on their personal guns. He's an artisan with black rifles, not just an assembler. He currently sources under-sized uppers and over-sized extensions for precision builds, and still uses Loc-tite. The problem I see with this is a lot of novices jumping in and incorporating this into their normal assembly procedure, especially on their first guns, where they spent $100 on a garbage barrel from Jim Bo's Tactical Start-Ups, with a chamber that is below minimum spec, they don't quite get the concept of gas block alignment with the ports, and then expect sub-MOA performance. Well said! $15.99 is NOT gonna buy you $3000.00 in performance. Shit, even spending a lot of dough on a full setup can give you headaches. Anyone remember my Wilson gas tube/gas block issue on my Mega? 'Cuz I am still trying to forget it. Understand points by both of you. Im using a criterion barrel to an Aero upper, JP adj gas block, it tests good flow by the air pressure, and rifle was test fired 12 times with 4 different ammo brands before tearing down for some cerakote and muzzle device work. I'm lapping the receiver prior to assembly, I was gonna do the loktite method, but thought I would see if there were any better options. I am not concerned with naysayers or the why bother group or prove it to me crowd, its my rifle..F them. Regarding the stainless shimming, how do you know where to put em, is there a testing/Measuring procedure ? |
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Posted: 5/1/2016 11:26:54 AM EDT
[#34]
Quote HistoryQuoted:
Regarding the stainless shimming, how do you know where to put em, is there a testing/Measuring procedure ? The kind of shim stock you need is like foil. Wrap it around the extension and check for fit. Actually, the product I would personally use is this 3M stainless steel foil tape. It's 2 mils thick (that's 0.002"), which will let you shim to a very fine tolerance. You can find 1" rolls of this (converted from wider rolls) on Amazon - I'd go with a 1" roll because that would help me keep the layers even. Before you start with a shim approach, you should know how much "slack" you need to shim for. Use a quality tool to measure both the bore of the upper and the OD of the barrel extension. You want to aim for enough shim to make the extension almost an interference fit, without going so far as to make it NOT fit. Let's say your upper measures 1.0080" ID, and your barrel measures 0.9990" OD. That's a difference of 0.0090", so 4 wraps of the 3M tape would give you a shimmed OD of 1.0070". If there's 1/1000" of "play" between your barrel extension and the upper, you're going to have to be very careful lining the barrel up to insert it. |
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Posted: 5/1/2016 11:42:10 AM EDT
[#35]
Quote HistoryQuoted:
The kind of shim stock you need is like foil. Wrap it around the extension and check for fit. Actually, the product I would personally use is this 3M stainless steel foil tape. It's 2 mils thick (that's 0.002"), which will let you shim to a very fine tolerance. You can find 1" rolls of this (converted from wider rolls) on Amazon - I'd go with a 1" roll because that would help me keep the layers even. Before you start with a shim approach, you should know how much "slack" you need to shim for. Use a quality tool to measure both the bore of the upper and the OD of the barrel extension. You want to aim for enough shim to make the extension almost an interference fit, without going so far as to make it NOT fit. Let's say your upper measures 1.0080" ID, and your barrel measures 0.9990" OD. That's a difference of 0.0090", so 4 wraps of the 3M tape would give you a shimmed OD of 1.0070". If there's 1/1000" of "play" between your barrel extension and the upper, you're going to have to be very careful lining the barrel up to insert it. Quote HistoryQuoted:
Quoted:
Regarding the stainless shimming, how do you know where to put em, is there a testing/Measuring procedure ? The kind of shim stock you need is like foil. Wrap it around the extension and check for fit. Actually, the product I would personally use is this 3M stainless steel foil tape. It's 2 mils thick (that's 0.002"), which will let you shim to a very fine tolerance. You can find 1" rolls of this (converted from wider rolls) on Amazon - I'd go with a 1" roll because that would help me keep the layers even. Before you start with a shim approach, you should know how much "slack" you need to shim for. Use a quality tool to measure both the bore of the upper and the OD of the barrel extension. You want to aim for enough shim to make the extension almost an interference fit, without going so far as to make it NOT fit. Let's say your upper measures 1.0080" ID, and your barrel measures 0.9990" OD. That's a difference of 0.0090", so 4 wraps of the 3M tape would give you a shimmed OD of 1.0070". If there's 1/1000" of "play" between your barrel extension and the upper, you're going to have to be very careful lining the barrel up to insert it. Thanks I have a decent set of calipers. |
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Posted: 5/1/2016 8:06:15 PM EDT
[#36]
Not sure if this has been said, i haven't read all the second page.
Not many mfgs bed the barrels because of one thing really, they can test fit multiple barrels to multiple uppers to get the best fit. Not all mfgs do this, but the good ones do. That's why you don't see many mfgs do this. Then, on the high precision builds, you don't see as much either because they either use known critically tight parts, or triple check everything further than the mass produced guys. You can find very tight fitting parts. Sometimes you gotta have multiple on hand. I didn't bed my MaTen because it didn't need it. The Armalite AR10T barrel was virgin tight all ready. Very snug. I didn't do it on this AR10 either because it too was already very snug. When s company had there production down, they don't need the extra help from certain techniques like bedding, or accuracy wedges, or what have you. But, these things can make sub par gear score birdies. Or, if you're sourcing parts from multiple parties, you'll find tolerances are not as tight across the board. Bedding the barrel is great assurance in these scenarios. It certainly doesn't hurt, and there have been unofficial tests of people noticing significant difference from sloppy fit barrels before and after bedding. Not every mfg uses the same techniques as the next guys. So, just because you don't see it in mass in the wild, doesn't mean is not a good idea. And before anyone says the military doesn't do it, remember they do the least amount possible that also costs the least. Not always does this recipe work well. |
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Posted: 5/1/2016 9:37:34 PM EDT
[#37]
Quote HistoryQuoted:
The kind of shim stock you need is like foil. Wrap it around the extension and check for fit. Actually, the product I would personally use is this 3M stainless steel foil tape. It's 2 mils thick (that's 0.002"), which will let you shim to a very fine tolerance. You can find 1" rolls of this (converted from wider rolls) on Amazon - I'd go with a 1" roll because that would help me keep the layers even. Before you start with a shim approach, you should know how much "slack" you need to shim for. Use a quality tool to measure both the bore of the upper and the OD of the barrel extension. You want to aim for enough shim to make the extension almost an interference fit, without going so far as to make it NOT fit. Let's say your upper measures 1.0080" ID, and your barrel measures 0.9990" OD. That's a difference of 0.0090", so 4 wraps of the 3M tape would give you a shimmed OD of 1.0070". If there's 1/1000" of "play" between your barrel extension and the upper, you're going to have to be very careful lining the barrel up to insert it. Quote HistoryQuoted:
Quoted:
Regarding the stainless shimming, how do you know where to put em, is there a testing/Measuring procedure ? The kind of shim stock you need is like foil. Wrap it around the extension and check for fit. Actually, the product I would personally use is this 3M stainless steel foil tape. It's 2 mils thick (that's 0.002"), which will let you shim to a very fine tolerance. You can find 1" rolls of this (converted from wider rolls) on Amazon - I'd go with a 1" roll because that would help me keep the layers even. Before you start with a shim approach, you should know how much "slack" you need to shim for. Use a quality tool to measure both the bore of the upper and the OD of the barrel extension. You want to aim for enough shim to make the extension almost an interference fit, without going so far as to make it NOT fit. Let's say your upper measures 1.0080" ID, and your barrel measures 0.9990" OD. That's a difference of 0.0090", so 4 wraps of the 3M tape would give you a shimmed OD of 1.0070". If there's 1/1000" of "play" between your barrel extension and the upper, you're going to have to be very careful lining the barrel up to insert it. The tape is 3.8 mils thick according to 3M page you linked. 2 mils of stainless and 1.8 mils of adhesive. Wonder if it stays that thick? Also if it was .002" thick and you fully wrapped your barrel 4 times that is .016". Each full wrap would add .004" to the diameter as the tape is adding .002" radially. |
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Posted: 5/1/2016 9:39:14 PM EDT
[#38]
Quoted:
Title says it. What compound, locktite or other ? None....not needed. |
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Posted: 5/2/2016 10:19:06 AM EDT
[#39]
Quote HistoryQuoted:
Understand points by both of you. Im using a criterion barrel to an Aero upper, JP adj gas block, it tests good flow by the air pressure, and rifle was test fired 12 times with 4 different ammo brands before tearing down for some cerakote and muzzle device work. I'm lapping the receiver prior to assembly, I was gonna do the loktite method, but thought I would see if there were any better options. I am not concerned with naysayers or the why bother group or prove it to me crowd, its my rifle..F them. Regarding the stainless shimming, how do you know where to put em, is there a testing/Measuring procedure ? Quote HistoryQuoted:
Quoted:
Quoted:
You can shim, thermo-fit, spec out interference fit parts, and some do combinations of these. A reputable precision rifle shop isn't just throwing the barrel in and torquing it, then calling it good. Higher torque is another approach with the barrel nut. If you look at the AMU and where this originated when a guy saw flex in his extension as he moved the barrel at a match down in Australia back when they had A1s, you can learn more about where it originated. There was a good video posted not too long ago where this was all detailed. I know guys that do precision work who have been doing it for almost 20 years. They've even tried JB Weld, glass bedding, you name it. One in particular doesn't have to advertise, and has done a lot of work for people in a certain unit in the Fort Bragg area, and continues to do work for guys from there on their personal guns. He's an artisan with black rifles, not just an assembler. He currently sources under-sized uppers and over-sized extensions for precision builds, and still uses Loc-tite. The problem I see with this is a lot of novices jumping in and incorporating this into their normal assembly procedure, especially on their first guns, where they spent $100 on a garbage barrel from Jim Bo's Tactical Start-Ups, with a chamber that is below minimum spec, they don't quite get the concept of gas block alignment with the ports, and then expect sub-MOA performance. Well said! $15.99 is NOT gonna buy you $3000.00 in performance. Shit, even spending a lot of dough on a full setup can give you headaches. Anyone remember my Wilson gas tube/gas block issue on my Mega? 'Cuz I am still trying to forget it. Understand points by both of you. Im using a criterion barrel to an Aero upper, JP adj gas block, it tests good flow by the air pressure, and rifle was test fired 12 times with 4 different ammo brands before tearing down for some cerakote and muzzle device work. I'm lapping the receiver prior to assembly, I was gonna do the loktite method, but thought I would see if there were any better options. I am not concerned with naysayers or the why bother group or prove it to me crowd, its my rifle..F them. Regarding the stainless shimming, how do you know where to put em, is there a testing/Measuring procedure ? Take 2 of these and call me in the morning. Hellbender's Guide Robert Whitley: What Makes an AR Accurate |
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Posted: 5/2/2016 10:38:48 AM EDT
[#40]
Take this with a grain of salt, this is the internet. I have read where someone on this or another forum did do a before and after test after bedding with loctite 620, green. He had about a 15% improvement in group size. I think this really depends on the fit on the barrel extension into the receiver. If yours fit is snug, bedding is probably not needed. If it is loose, shimming or bedding is probably not a bad idea. I guess it depends if it worth 15% or not. To me it is if it actually improves the group.
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Posted: 5/2/2016 12:41:28 PM EDT
[#41]
Quote HistoryQuoted:
Take 2 of these and call me in the morning. Hellbender's Guide Robert Whitley: What Makes an AR Accurate Quote HistoryQuoted:
Quoted:
Quoted:
Quoted:
You can shim, thermo-fit, spec out interference fit parts, and some do combinations of these. A reputable precision rifle shop isn't just throwing the barrel in and torquing it, then calling it good. Higher torque is another approach with the barrel nut. If you look at the AMU and where this originated when a guy saw flex in his extension as he moved the barrel at a match down in Australia back when they had A1s, you can learn more about where it originated. There was a good video posted not too long ago where this was all detailed. I know guys that do precision work who have been doing it for almost 20 years. They've even tried JB Weld, glass bedding, you name it. One in particular doesn't have to advertise, and has done a lot of work for people in a certain unit in the Fort Bragg area, and continues to do work for guys from there on their personal guns. He's an artisan with black rifles, not just an assembler. He currently sources under-sized uppers and over-sized extensions for precision builds, and still uses Loc-tite. The problem I see with this is a lot of novices jumping in and incorporating this into their normal assembly procedure, especially on their first guns, where they spent $100 on a garbage barrel from Jim Bo's Tactical Start-Ups, with a chamber that is below minimum spec, they don't quite get the concept of gas block alignment with the ports, and then expect sub-MOA performance. Well said! $15.99 is NOT gonna buy you $3000.00 in performance. Shit, even spending a lot of dough on a full setup can give you headaches. Anyone remember my Wilson gas tube/gas block issue on my Mega? 'Cuz I am still trying to forget it. Understand points by both of you. Im using a criterion barrel to an Aero upper, JP adj gas block, it tests good flow by the air pressure, and rifle was test fired 12 times with 4 different ammo brands before tearing down for some cerakote and muzzle device work. I'm lapping the receiver prior to assembly, I was gonna do the loktite method, but thought I would see if there were any better options. I am not concerned with naysayers or the why bother group or prove it to me crowd, its my rifle..F them. Regarding the stainless shimming, how do you know where to put em, is there a testing/Measuring procedure ? Take 2 of these and call me in the morning. Hellbender's Guide Robert Whitley: What Makes an AR Accurate I have read hellbenders..like it. Thanks for the other link as well, gonna read it at work. |
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Posted: 5/2/2016 1:24:14 PM EDT
[#42]
Quote HistoryQuoted:
Take this with a grain of salt, this is the internet. I have read where someone on this or another forum did do a before and after test after bedding with loctite 620, green. He had about a 15% improvement in group size. I think this really depends on the fit on the barrel extension into the receiver. If yours fit is snug, bedding is probably not needed. If it is loose, shimming or bedding is probably not a bad idea. I guess it depends if it worth 15% or not. To me it is if it actually improves the group. I personally have seen groups shrink on several AR15s and AR10s now from 1.5" to 1.7", down to the .3" to .6" range, even in a new shooter's hands. Barrels I have seen this with: JP Krieger Lilja The common thread between all the cases so far? Initially assembled with loose fit, no squared upper receiver, and no bedding compound. After they were lapped, bedded, and torqued, with the same loads, groups shrunk by more than half. I also built up Cerakote inside the extension tunnel in the uppers of some of them after lapping the face, and I always use some type of adhesive compound, even when there is an interference fit, applying it circumferentially around the extension after starting it into the tunnel. My 1000yd groups don't lie either, and when you start to see a pattern with shops that are known for extreme accuracy in the AR15, I think it's prudent to pay attention. A lot of these techniques were somewhat guarded for many years, as people didn't want to share their competitive advantages. Balanced torque on your optics mounts is another. Same with zero torque on muzzle devices and Rocksett. |
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Posted: 5/2/2016 1:36:48 PM EDT
[#43]
Quote HistoryQuoted:
I personally have seen groups shrink on several AR15s and AR10s now from 1.5" to 1.7", down to the .3" to .6" range, even in a new shooter's hands. Barrels I have seen this with: JP Krieger Lilja The common thread between all the cases so far? Initially assembled with loose fit, no squared upper receiver, and no bedding compound. After they were lapped, bedded, and torqued, with the same loads, groups shrunk by more than half. I also built up Cerakote inside the extension tunnel in the uppers of some of them after lapping the face, and I always use some type of adhesive compound, even when there is an interference fit, applying it circumferentially around the extension after starting it into the tunnel. My 1000yd groups don't lie either, and when you start to see a pattern with shops that are known for extreme accuracy in the AR15, I think it's prudent to pay attention. A lot of these techniques were somewhat guarded for many years, as people didn't want to share their competitive advantages. Balanced torque on your optics mounts is another. Same with zero torque on muzzle devices and Rocksett. Quote HistoryQuoted:
Quoted:
Take this with a grain of salt, this is the internet. I have read where someone on this or another forum did do a before and after test after bedding with loctite 620, green. He had about a 15% improvement in group size. I think this really depends on the fit on the barrel extension into the receiver. If yours fit is snug, bedding is probably not needed. If it is loose, shimming or bedding is probably not a bad idea. I guess it depends if it worth 15% or not. To me it is if it actually improves the group. I personally have seen groups shrink on several AR15s and AR10s now from 1.5" to 1.7", down to the .3" to .6" range, even in a new shooter's hands. Barrels I have seen this with: JP Krieger Lilja The common thread between all the cases so far? Initially assembled with loose fit, no squared upper receiver, and no bedding compound. After they were lapped, bedded, and torqued, with the same loads, groups shrunk by more than half. I also built up Cerakote inside the extension tunnel in the uppers of some of them after lapping the face, and I always use some type of adhesive compound, even when there is an interference fit, applying it circumferentially around the extension after starting it into the tunnel. My 1000yd groups don't lie either, and when you start to see a pattern with shops that are known for extreme accuracy in the AR15, I think it's prudent to pay attention. A lot of these techniques were somewhat guarded for many years, as people didn't want to share their competitive advantages. Balanced torque on your optics mounts is another. Same with zero torque on muzzle devices and Rocksett. I'm listening. Please elaborate. |
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Posted: 5/2/2016 2:10:21 PM EDT
[#44]
The theory is, the torque on the muzzle end changes barrel harmonics. Not much else going on.
No torque, well, a bit more than hand tight is say. Shim it to time, use Rockset to lock it in place. I just say don't use a muzzle. There is no muzzle that increases accuracy of the barrel. It's all about follow up shots for muzzles. No muzzle threading, a good crown, proper tapered profile, cutting at the right point in the rifling, harmonics are the key. |
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Posted: 5/2/2016 2:43:19 PM EDT
[#45]
Quote HistoryQuoted:
The theory is, the torque on the muzzle end changes barrel harmonics. Not much else going on. No torque, well, a bit more than hand tight is say. Shim it to time, use Rockset to lock it in place. I just say don't use a muzzle. There is no muzzle that increases accuracy of the barrel. It's all about follow up shots for muzzles. No muzzle threading, a good crown, proper tapered profile, cutting at the right point in the rifling, harmonics are the key. Got a 24 bull that is threaded, will have brake installed. That's why it got my attention, I had not heard of that one before. Smith is building me one, cause I wanted a one of a kind, gonna tell him to time it that way. So how hand tight is no torque, serious question ? |
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Posted: 5/2/2016 4:56:20 PM EDT
[#46]
The more torque you put on the soft steel muzzle, the more probability there is to jack up your muzzle as the bullet passes through.
With precision shims, you can clock it without torque. A few inch pounds isn't going to do anything. It's really when people do the normal approach of calling in cousin Cleatus and the cheater bar, and start hanging off the gun, with upper in the vice of course. |
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Posted: 5/2/2016 5:01:31 PM EDT
[#47]
Quote HistoryQuoted:
The more torque you put on the soft steel muzzle, the more probability there is to jack up your muzzle as the bullet passes through. With precision shims, you can clock it without torque. A few inch pounds isn't going to do anything. It's really when people do the normal approach of calling in cousin Cleatus and the cheater bar, and start hanging off the gun, with upper in the vice of course. Cletus is doing time for running shine, so he wont be around to help. Just left the lgs and talked to smith, he hasn't started on my brake yet. Told him I wanted to time it with firm hand pressure and Rocksett, he said now you're talking, now go away so I can get some work done. 
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Posted: 5/2/2016 7:39:41 PM EDT
[#48]
Go hand tight, put the wrench in it, give it a slight tap. Really you want it just past hand tight. Like double fisted tight.
Like LRRP, inch pounds instead of foot pounds. If you've got a torque wrench, and it won't do inch pounds, just set between 5-10lbs. That should do it. You'll need a hefty set of different sized shims to get it right. Your smith will hopefully have enough. Not that it'll use them all, just so you have s bunch of sizes to find the right combo. It's say hand tight to 11:00-11:30, wrench the rest of the way. That should do the trick |
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Posted: 5/2/2016 8:14:37 PM EDT
[#49]
I'm talking more like 11:57, fine tune the clock for TDC, with appropriate compound.
Be aware that thread locking compound will change the coefficient of friction on the threads, so your test-drive for shimming won't be the same, and you need to account for this. |
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Posted: 5/2/2016 8:18:37 PM EDT
[#50]
Quote HistoryQuoted:
The tape is 3.8 mils thick according to 3M page you linked. 2 mils of stainless and 1.8 mils of adhesive. Wonder if it stays that thick? Also if it was .002" thick and you fully wrapped your barrel 4 times that is .016". Each full wrap would add .004" to the diameter as the tape is adding .002" radially. The point of "bedding" an AR barrel is to make sure it's centered in the upper when you install the barrel nut. 30 foot-pounds of torque will apply a substantial amount of clamping force on the barrel's flange. This retains the barrel in the upper exactly where you put it. |
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