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Tighten that castle nut

cmshoot

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I was talking with a guy that does a lot of the Armorer work at the gas gun precision rifle match that Knight’s Armament sponsors at Arena Training Facility twice a year.

He said that the most common repair he does there is tightening castle nuts that have become loose under firing. They come loose because they are not staked, or otherwise held in place

This is why the spec calls for the castle nut to be staked twice.

If you have some kind of aversion to proper staking, or you have a receiver end plate that cannot be staked because it’s made of aluminum, titanium, Unobtainium, or overly hard/brittle steel (I’m looking at you, Magpul), then I highly recommend Vibra-TITE VC-3. Unlike Loctite or Rocksett, VC-3 sets to a rubber-like consistency. No issues with future disassembly using simple hand tools, but it won’t vibrate loose on its own. Remember to degrease the receiver extension and castle nut before use.

VC-3 is also an excellent option if you are regularly disassembling this part of your AR. It is relatively easy to clean off threads and parts.
 
Slight welding seems to work as well…….

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this is why is like the ratcheting one from PWS. no need to do anything other than get it good and tight. no staking required

Those are designed for folks that like to take them apart and put them back together. Do it a few times, the ratcheting part wears out, and it stops retaining itself. Not a solid design. I’ve seen more than one come loose.
 
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