View Full Version : Barrel installation question... red loctite?
midSCarolina
06-18-13, 13:58
Kinda a rookie build question so I apologize. I saw some guy putting red loctite on the barrel extension prior to installing the barrel into the upper receiver. It didn't look like an awesome idea to me but maybe I'm wrong bc I have always just kinda stuck the barrel in without any special products or anything. Does anyone here put anything on the barrel extension prior to install? Thanks
It's called bedding and its been discussed here at great length.
Red Loctite isn't the right choice.
If its of any benefit depends on the parts used, quality of the ammunition and the skill of the shooter. It won't make a 2 MOA gun a 1/2 MOA one, but can perhaps influence a 3/4 MOA gun closer to a 1/2 MOA one.
midSCarolina
06-18-13, 14:05
Thanks... i apologize and look it up. I just didn't know what it was called.
Don't assemble anything with RED that you ever want to take apart without a torch! GH
Mauser KAR98K
06-18-13, 19:27
Loctite on anything barrel related is a big no-no.
Use a none-lithium grease around the threads where the barrel nut screws on to, and tighten down between 30-50 foot pounds. Once that is done, untighten the barrel and repeat this process two more times before tightening down the barrel nut the last time, making sure the gas tube can be inserted unobstructed and does not touch the receiver or the barrel nut.
Loctite on anything barrel related is a big no-no.
Use a none-lithium grease around the threads where the barrel nut screws on to, and tighten down between 30-50 foot pounds. Once that is done, untighten the barrel and repeat this process two more times before tightening down the barrel nut the last time, making sure the gas tube can be inserted unobstructed and does not touch the receiver or the barrel nut.
Not to highjack the thread, but what if you do not do that? I just applied grease, torqued to 30 foot pounds, then went to 50. I have heard of tightening and loosening the nut a couple times here, but I never recall as to why.
Does that ensure the barrel nut will not come loose?
Not to highjack the thread, but what if you do not do that? I just applied grease, torqued to 30 foot pounds, then went to 50. I have heard of tightening and loosening the nut a couple times here, but I never recall as to why.
Does that ensure the barrel nut will not come loose?
Nothing. Some people are just anal. The barrel nut won't loosen if you torqued it to the proper spec once. You're not going to gain another tooth on the barrel nut by doing it three times.
Metal stretches as it is torqued. This is why it's done three times.
Also, don't use a blow torch to loosen Loctite parts, use a heat gun.
Loctite on anything barrel related is a big no-no.
Use a none-lithium grease around the threads where the barrel nut screws on to, and tighten down between 30-50 foot pounds. Once that is done, untighten the barrel and repeat this process two more times before tightening down the barrel nut the last time, making sure the gas tube can be inserted unobstructed and does not touch the receiver or the barrel nut.
Why not use what the Mil-Spec calls for?
Www.ucwrg.com/materiel/weapon-lubrication/18/aeroshell-33ms-grease/
Just askin'...
Rascal
The reason for repeat torquing is so that the fastening system retains the set torque spec. Threaded fasteners are nothing more than helical wedges. As the mating surfaces of the two components slide across one another they "wear in". The peaks on the surface finish are worn down with each torquing. Part of the resistance during torquing is the stretching of the metal. The other part is the friction of rotation. As the parts wear in, a larger portion of the resistance is the stretch and a smaller portion the friction. Torquing three times brings the stretch closer to the ideal fastening force.
The reason for repeat torquing is so that the fastening system retains the set torque spec. Threaded fasteners are nothing more than helical wedges. As the mating surfaces of the two components slide across one another they "wear in". The peaks on the surface finish are worn down with each torquing. Part of the resistance during torquing is the stretching of the metal. The other part is the friction of rotation. As the parts wear in, a larger portion of the resistance is the stretch and a smaller portion the friction. Torquing three times brings the stretch closer to the ideal fastening force.
Thanks, and thanks to everyone else.
So then, is it even worth the trouble to retorque it? Or should I be good? The barrel nut is not loose for the 500 rounds I put through this new rifle. The Daniel Defense directions only mentioned torquing to 50, so that is what I did.
midSCarolina
06-18-13, 21:45
Thanks for all of the good info... i have built several ARs with the help of a friend (used the moly grease but didn't torque and re-torque) so this will be my first complete solo build and when i saw some ppl doing it different I just wanted to check because these builds get expensive and I want to do it correctly.
themissinglink
06-18-13, 21:56
Once had to remove a red loctited fastener. The torch was the only thing that worked! Needless to say, i don't particularly like red loctite :)
When those guys are talking about using red loctite they are putting a few drops around the barrel extension and inserting it in the upper receiver, not on the threads. A bunch of heat from a heat gun and knock it out with a dowel if you need to replace it. Not that'd I'd bother to do it, but that's the way I've read it being done.
The Loctite I would use, and did...is Loctite 609, which is typed as being a sleeve retainer compound.
Its green.
For what its worth, out of a Noveske Afghan, with limited load development the gun routinely shoots 3/4 MOA groups, with the best being .462"
Mauser KAR98K
06-19-13, 00:30
Why not use what the Mil-Spec calls for?
Www.ucwrg.com/materiel/weapon-lubrication/18/aeroshell-33ms-grease/
Just askin'...
Rascal
Because it's not in stock, and the Valvoline works well, too.
When those guys are talking about using red loctite they are putting a few drops around the barrel extension and inserting it in the upper receiver, not on the threads. A bunch of heat from a heat gun and knock it out with a dowel if you need to replace it. Not that'd I'd bother to do it, but that's the way I've read it being done.
Why on Earth would people loctite the extension to the upper? Do they not trust their skills, or think they might want to take the barrel out?
midSCarolina
06-19-13, 09:21
Because it's not in stock, and the Valvoline works well, too.
Why on Earth would people loctite the extension to the upper? Do they not trust their skills, or think they might want to take the barrel out?
I have no idea... i just wanted to get a visual reference for drilling dimples and next thing i know this dude is smearing red loctite all over his barrel extension. Check it out (5:37) http://www.youtube.com/watch?v=GtDNVru966g
I've got a JP Ent. free float hand guard that hasn't been mounted yet.
The instruction set call for using RED Loc-tite on what is called a "outer receiver nut" where it threads onto the upper receiver forging.
This "nut" -doesn't- by itself, hold the barrel on, but acts as a "thread converter" (outside-to-inside). It is explained that the "nut" could turn while torqueing the barrel nut and consequently looseing the line up of the gas tube channel between the receiver and the "nut".
I have always looked at RED Loc-tite as a coarse and difficult substance to use, but, the folks at JP -ARE- leaders in thier field. The instructions go so far as to explain how to defeat the Loc-tite RED271 using a propane torch and a specific temperature.
I still consider it sort of scary, and will probably trade messages with the JP support folks before I spill the RED271 on my gun's threads.
Lord knows, I'd certainly NEVER use it anywhere else that I ever contemplated needing to dismantle for kicks or giggles.
I don't know that I have ever heard of red used on anything, but then again I have never built my own so this is some good information!
As to why someone would consider using the Loc-tite RED271 as a bedding compound, the JP instruction sheet says that the stuff will degrade to a "white powder when subjected to 400-450 degrees F." .
I think that just might be beyond the temperature reached while extended/rapid fire of the rifle.
It also doesn't shrink, and it is mighty tough when it has hardened, but...
The problem I'd see in using it for that purpose is that it sets up -or- hardens (in the short term, anyway) in an enviroment lacking in oxygen.
Sure it WILL dry out and fill gaps and such, but it takes a loonnnggg time when used in an enviroment other than it is intended for.
Heavy Metal
06-19-13, 11:06
The Loctite I would use, and did...is Loctite 609, which is typed as being a sleeve retainer compound.
Its green.
For what its worth, out of a Noveske Afghan, with limited load development the gun routinely shoots 3/4 MOA groups, with the best being .462"
I hope you like that barrel where it is because you ain't removing it ever! That sleve retainer compound is the most agressive stuff made from a strength standpoint.
609 Loctite will not release until it is heated to about 700*F - 800*F. When I had to remove a sleeve type front sight base I installed using 609 the steel turned a light straw color before it let go.
609 can also set up VERY fast. That is why I had to remove the sight base. The 609 setup before I got the sight aligned - like about 5 min.
Heavy Metal
06-19-13, 11:28
What is 800 degrees going to do to an aluminum reciever?
I've got a JP Ent. free float hand guard that hasn't been mounted yet.
The instruction set call for using RED Loc-tite on what is called a "outer receiver nut" where it threads onto the upper receiver forging.
This "nut" -doesn't- by itself, hold the barrel on, but acts as a "thread converter" (outside-to-inside). It is explained that the "nut" could turn while torqueing the barrel nut and consequently looseing the line up of the gas tube channel between the receiver and the "nut".
Just a note, put the locktite on the threads on the receiver, not on the "outer receiver nut." This way, the locktite only gets on the part of the threads of the "outer receiver nut" that go on the receiver. The forward portions of the threads will hold their "steel inner
barrel retainer nut" and will end up with moly grease on them.
From the JP instructions:
3. Using red LoctiteŽ 271, coat the threads of the receiver barrel collar. Install the aluminum outer receiver nut, ...
4. Insert the barrel extension piece into the upper receiver. Apply an anti-seize compound to the threads of the steel inner barrel retainer nut. .. Insert the steel barrel retainer nut and screw it into the aluminum receiver nut until you have tensioned the aluminum outer nut on the receiver hand tight ... Let that set overnight so that the LoctiteŽ cures thoroughly.
I literally just mounted one of these over the last two days.
Nothing. Some people are just anal. The barrel nut won't loosen if you torqued it to the proper spec once. You're not going to gain another tooth on the barrel nut by doing it three times.
Maybe not another whole tooth, but it can get you more room. On the JP handguard install mentioned above, I did the torque 2x at 30 ft-lb thing, then I always set my torque wrench to 80 ft-lb so I know if I'm at the upper limit. It clicked about an 1/8-1/4 tooth short of where I needed to be. I backed it off, torqued to 50 ft-lb, backed off again, and then it tighted in alignment under 80.
Note the JP instructions do not mention the 3x torque steps.
-rvb
I hope you like that barrel where it is because you ain't removing it ever! That sleve retainer compound is the most agressive stuff made from a strength standpoint.
No its not. I've actually removed two before. There are MUCH more aggressive Loctite compounds. The heat I applied was from a heat gun, and also broke down the Loctite on the URX rail from the receiver.
The final strength of Loctite depends on the materials involved. Steel to steel is the strongest, while stainless steel results in a very weak bond by comparison. Some materials and when used with some coatings even require a primer or the Loctite won't cure.
609 Loctite will not release until it is heated to about 700*F - 800*F.
Incorrect. The release temperature is 250 C which is 482 F. This is from the products data sheet.
http://tds.loctite.com/tds5/docs/609-EN.pdf
The heating involved wouldn't effect 7075 series aluminum. Annealing is accomplished at 775 F, sustained for two to three hours then controlled cooled.
It's called bedding and its been discussed here at great length.
Red Loctite isn't the right choice.
If its of any benefit depends on the parts used, quality of the ammunition and the skill of the shooter. It won't make a 2 MOA gun a 1/2 MOA one, but can perhaps influence a 3/4 MOA gun closer to a 1/2 MOA one.
This is exactly what its for. There is no point or need to use red loctite though - blue will do fine. Contrary to popular believe the barrel extension doesn't get that hot by comparison with further down the barrel - and even if it did, the loctite is purely there in these cases as a bedding compound rather than to "stick" anything together. The compound would still retain its bedding capability - it doesn't melt even when heated, it just goes more brittle and for this particular purpose that'd be fine.
If you use blue, come barrel removal time its as easy as lightly tapping the receiver off the barrel with a rubber mallet - I've done a few.
Most professionals use duct tape.:p
justin_247
06-19-13, 20:02
I have no idea... i just wanted to get a visual reference for drilling dimples and next thing i know this dude is smearing red loctite all over his barrel extension. Check it out (5:37) http://www.youtube.com/watch?v=GtDNVru966g
That was painful to watch.
Jeese, the one after that is horrible, too. After he applies a metric ton of loctite and wipes most of it off, he's then obsessed with the application of the grease.
I stand corrected re release temp for Loctite 609. The product I used was Loctite 620 high strength retaining compound, not 609.
Not withstanding Loctite's stated release temperature for 620, using an industrial heat gun I have had to set the heat gun to 750*F to get it to release. I have also used "Temp Sticks" to verify this temp because I thought the heat gun was not calibrated correctly.
Setting the same heat gun to 450*F works fine for 271 if torque is applied while heating.
Good info. I had never heard about locktight (bedding) on a AR. Learn something new every day.
I'd like to add something in return. If you need to remove a lock-tighted screw or hex screw, you can use a solder iron. Hold the iron (when its up to temp) on the screw for a 10 - 20 seconds, and try to loosen. If it does not want to turn easily, hold the iron on again. It should come off easily after 2 or 3 times. You can also hold the screwdriver/ allen wrench in a propane torch flame, or even a candle. Hold it on the screw for a few seconds and give a gentle twist, repeat till it comes off.
This way you don't have to heat/discolor a large portion of whatever you are working on.
That's why I always liked heat guns. Gets the parts hot without the burning & scorching.
midSCarolina
06-21-13, 14:10
One last question... i have ordered a jig so i can drill the dimples but the barrel already has one. Do i even need to drill the second or is one good to go? Thanks
Your call. One will hold it if you put some rocket in the set screw or something.
Use Loc-tite 271 and put them in. If you have the screws with the teeth that dig in you will have no issues at all.
One last question... i have ordered a jig so i can drill the dimples but the barrel already has one. Do i even need to drill the second or is one good to go? Thanks
Use Loc-tite 271 and put them in. If you have the screws with the teeth that dig in you will have no issues at all.
Yep.. I used to be very skeptical about these lo pro blocks... but I've not read one account of someone's getting blown out of position.
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