Gunsmithing AR assembly question

[supernt]

When installing a new barrel in an upper, is it a recommended practice to use grease or anti-seize. Maybe loctite.

Also the barrel nut. I have only seen a few, but I have seen one that was installed with loctite. All others had grease.

This is the first time I have done this and want to make sure I do it correctly.

Thank you

 

[veezer]

Re: AR assembly question

All the ones that I have taken off of factory guns had white grease.

 

[marduk185]

Re: AR assembly question

on the few builds ive done i havent used anything like that. seems unnecessary and possibly problematic especially if you plan to swap later.

 

[doc76251]

Re: AR assembly question

I assemble mine with DSX assemby lube. Once they are together and fitted correctly I'll pull it apart and use anti sieze on the threads and on the end of the gas tube.

FWIW it may take several "Assemblies" to get the lock ring to seat fully. If you do it once you may find yourself with a loose barrel after a couple hundred rounds. Hence the above method.

Cheers,

Doc

 

[TacticalSasquach]

Re: AR assembly question

If you have a gas tube, the barrel nut cannot come undone.If so the rifle would become inoperable immediately

 

[doc76251]

Re: AR assembly question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cobb_50</div><div class="ubbcode-body">If you have a gas tube, the barrel nut cannot come undone.If so the rifle would become inoperable immediately </div></div>

That is the end result. For the first time builder he/she may not know the feel difference of the lock righ bottoming out or the phosphate finish binding up and hitting the desired tourque. It aint much but I've had it happen once and seen it more than that with table top guns.

Cheers,

Doc

 

[LoneWolfUSMC]

Re: AR assembly question

Molly Grease. Tighten to spec then line the notch up for the gas tube if necessary. If you need to line up a notch to to the NEXT tighter notch, do not back it off.

 

[Outsydlooknin75]

Re: AR assembly question

Use Moly grease, tighten to 30 to 80 ft pounds you should be able to get a spot to line up somewhere in that torque range. If not tighten and loosen multiple times sometimes a t/l needs to be done 3 to 5 times before you get it right. Once you insert the gas tube the nut will never be allowed to back out and loosen to where the barrel will fall off. Dont use a white litium grease it will act like a salt and erode the metal over time. The only reason you use grease on the threads is to keep the two different metals from galling together.

 

[salmonaxe]

Re: AR assembly question

I'm pretty darn sure that all moly grease you will find is of Lithium base.

I've never had a problem with the valvoline mutipurpose moly fortified grease. (I use it on wheel bearings too.)

http://www.valvoline.com/products/brands/valvoline/grease/65

All threads and anodizing on that I've removed that used that grease were fine.

I think the only issue that can ever occur is if the wrong type of antiseize is used and potentially helps or doesn't block galvanic reaction between steel and aluminum. Suggested antiseize for steel to aluminum uses Zinc as a base.

 

[supernt]

Re: AR assembly question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Salmonaxe</div><div class="ubbcode-body">I'm pretty darn sure that all moly grease you will find is of Lithium base.

I've never had a problem with the valvoline mutipurpose moly fortified grease. (I use it on wheel bearings too.)

http://www.valvoline.com/products/brands/valvoline/grease/65

All threads and anodizing on that I've removed that used that grease were fine.

I think the only issue that can ever occur is if the wrong type of antiseize is used and potentially helps or doesn't block galvanic reaction between steel and aluminum. Suggested antiseize for steel to aluminum uses Zinc as a base. </div></div>

Lithium based and moly fortified greases are different. I will have to research it, but I beleive molybednum disulfide is a powder like graphite. I think I remember learning that molybednum disulfide is a good grease when two non-bearing metal surfaces may contact each other. It provides a barrier between the two surfaces.

I will re-educate myself today.

Thanks everyone for their input

 

[salmonaxe]

Re: AR assembly question

Fortified- D: to add material to for strengthening or enriching <fortified milk>

If a grease is fortified with moly, there has to be a base grease which is being fortified. When looking around all I've ever been able to find is moly fortified grease with a lithium base. I really don't believe that it's possible to have a true moly based grease. I've seen a moly paste which contained 60% moly...

http://en.wikipedia.org/wiki/Grease_(lubricant)

Mainly I was trying to point out that their should be no real effect on aluminum by using a lithium based grease. By itself it's supposed to be non corrosive. From what I've gathered the lithium compound that is in lithium grease called lithium stearate and doesn't have the corrosive properties of pure lithium. (Which by itself is not supposed to occur in nature. Pure lithium is one of the alkali metals which are very reactive.)

It's graphite or copper which can cause a potential galvanic reaction with aluminum. Due to their nobility in the Galvanic series. Molybdenum is far away on the galvanic scale from aluminum, but from what I've read the chemical compound Molybdenum disulfide is non reactive.