Build Thread AR-15 Build Question- Castle Nut

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So I'm so close to finishing my first build. And I'm not sure how to make sure the castle nut is on tight! How do I know if it's tight enough (but not too tight)? Is there a specific tool I can purchase?
 

Mygrainman

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40 ft pounds is the recommended... good and snug.
And you can always stake it (take a chisel or center punch to the end plate at one of the inside divots on the castle nut)... if you want to make sure it doesn’t back off.
personally I never do because I change parts around too often.

There is a spanner on most universal ar wrenches that you can use for the job.
 
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I usually do stake my castle nuts. I've had to repair a few friends AR pistols where the castle nut backed out and allowed the tube to thread out enough where the buffer spring detent popped out, lodged in the FCG and just created general havoc. On an AR pistol tubes without a brace it's easy to miss a tube that's backing out. The stake is not permanent but just enough to keep the castle nut from moving. Nothing more frustrating than having the castle nut on any rifle come loose at the range.

I just use a pneumatic center punch to do a clean, tidy stake on all of my castle nuts. Easy peasy!

https://www.amazon.com/dp/B07KXKRF1...&pd_rd_r=a74a62ac-699e-11e9-94bd-393e388bbf8d
 

Mygrainman

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When Larry / Iron Monster (R.I.P. brother:rolleyes:) and I built the give away gun for Ed... the last thing he did before we packed it up to test fire was to stake the nut. He said that little things like that show the end user that whomever built it, took pride in the job and did it right...
The guy was a craftsman.... and I was lucky to have learned from him.
When I help friends build their lowers... I’ll recommend that they do stake as well. End plates are cheap, and it takes all of 10 seconds to do.
I just don’t stake my own because of my tendency to “rebuild” them constantly. But as part of my regular cleaning and maintenance... I check them for snugness, and re-torque as necessary.
 
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So I'm so close to finishing my first build. And I'm not sure how to make sure the castle nut is on tight! How do I know if it's tight enough (but not too tight)? Is there a specific tool I can purchase?
Officially it's 38-42 ft lbs in the M16/M4 Tech Manual.
And they want you to use your barrel nut grease on those threads as well.
If you've worked on cars, etc. you can "feel" that without a torque wrench.
Better castle nut wrenches have a provision (read square hole) for attaching a torque wrench.

This is what a castle nut staking looks like...
DIYstaking-1.jpg
 

Geardo

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I usually stake and loctite castle nuts.

I have 2 castle nut tools, but both are kind of crappy.
Buy a good armorers wrench with an open end castle nut wrench. That way you can hold on to the stock to keep everything square as you tighten it.
 

Tony617

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I know my castle nuts are staked on my rifles that I bought fully assembled but my home built ones aren’t staked. I torque it down only and have not put any loctite on them. I have never had the castle nut come loose with my home built ARs.

I ordered a castle nut wrench from EBay.
 

Tony617

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Respectfully ...

Do not stake. Use an adequate amount of Blue Lock Tight. Torque up until very snug. No more. For that matter no staking anywhere in the build.

Reasoning based upon vast experience. (?) Why ding up parts to keep them. This includes the carrier key screws. Use RED Lock Tight there AFTER the key and gas tube have been perfectly aligned with the barrel nut. OEM parts.

Sometimes the GI manuals are wrong. Yep.

Respectfully.

Hundreds of AR15 builds. Uncounted M16 rebuilds. All long ago and far away. Now old. Yikes! :)
 

Geardo

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Respectfully ...

Do not stake. Use an adequate amount of Blue Lock Tight. Torque up until very snug. No more. For that matter no staking anywhere in the build.

Reasoning based upon vast experience. (?) Why ding up parts to keep them. This includes the carrier key screws. Use RED Lock Tight there AFTER the key and gas tube have been perfectly aligned with the barrel nut. OEM parts.

Sometimes the GI manuals are wrong. Yep.

Respectfully.

Hundreds of AR15 builds. Uncounted M16 rebuilds. All long ago and far away. Now old. Yikes! :)

Its a 4 dollar part on a gun that coukd save your life. Who cares about dinging it!
 

Geardo

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If you even MIGHT want to try out different buffer systems like A5 or Super 42, PWS also makes it easier to swap those. (My "ideal" tail-swap would be a LAW sidefolder and spare back ends for it, but LAW never responded to my suggesting the idea and asking for an estimate.)

They true answer their is just build more guns!
 

titsonritz

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Respectfully ...

Do not stake. Use an adequate amount of Blue Lock Tight. Torque up until very snug. No more. For that matter no staking anywhere in the build.

Reasoning based upon vast experience. (?) Why ding up parts to keep them. This includes the carrier key screws. Use RED Lock Tight there AFTER the key and gas tube have been perfectly aligned with the barrel nut. OEM parts.

Sometimes the GI manuals are wrong. Yep.

Respectfully.

Hundreds of AR15 builds. Uncounted M16 rebuilds. All long ago and far away. Now old. Yikes! :)
Ah...no, thanks. I'll continue to stake castle nuts and use ‎Ned Christiansen's MOACKS and OCKS for carrier keys.
 

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