Question about Castle Nuts. (AR-15)

[MoDerN_WarRioR]

OK so... I went to the Gun show in AZ a few days ago and I purchased a new Castle Nut for my AR15 because i scratched mine all up trying to install my single point sling adapter.

I was thinking all buffer tube threads (the part that threads into the lower) where the same on all AR's. BUT i took my old Castle Nut off and went to screw on the new Castle Nut and it started to thread on about 2-3 rotations then it would get crooked and stop threading.

So I'm just wondering if there is a difference in Commercial threads vs Mil spec threads. OR could it possibly just be the Castle nut is milled wrong? And i do know the difference with the Butt stocks being different between the 2 spec's but would the threads ALSO be different? Thanks!!

-Chris

p.s. My gun is a Com spec DPMS buffer/tube

 

[carbine85]

The Mil spec tube is not the same size however I'm not 100% sure about the threads. The threads should be the same given the fact that you can change out the tubes one for the other. Does your old castle nut thread on ok? I'm guessing your new on is the problem.

 

[MrCleanOK]

Threads are the same size on commercial and milspec tubes. Check threads on the tube and nut for damage/defects.

 

[The_Hammer_Man]

Seen this before with patrol rifles (CAR-15's) w/ staked castle nuts. IE, someone during installation of the buffer tube took a staking tool and "permanently mounted" it. (yeah right!)

A little blue locktite works better and doesn't screw up the nut or the threads.

You could also have a bad/cheap aftermarket,(IE, chinese or korean) of less than perfect threading.

Do as the above responder suggested and check the thread count on your "new" CN against your "old" one.

 

[taliv]

threads are the same. cheap gun-show parts are most likely the problem.

you are supposed to stake the castle nuts, not use lock tite. actually, you stake the receiver end-plate. you are not supposed to stake the threads

 

[MoDerN_WarRioR]

Well i think this answered my question. Im like 99.9% sure its the stupid new Castle Nut. It does have rough edges like it was made cheap. and my old one actually goes on very easily so i know it isnt the buffer tube threads. Also my gun has never been staked or Loc-Tite'ed

I guess its not the worst thing i have ever blown 8 bucks on. LoL

*Any one wanna buy a NEW Castle nut? Never been installed! hehe

Thanks guys!

 

[HOLY DIVER]

i'd get my castle nut from midway or bravo company, i learned the hard way to stay away from gunshow AR-15 parts

 

[MrCleanOK]

Definitely stake the end plate when you put it back together (or use a new end plate, if the old one was staked). Staking is meant to make the castle nut stay on, AND be easily removable. The castle nut should not get loc-tite of any kind. This is what can happen when you use loctite:


(Not my image, I just googled it)

Yes, that is a ripped off thread. Aluminum threads and loctite DO NOT GET ALONG.

 

[DBR]

Proper staking is the right way to retain the castle nut. If Loctite is used it should be Loctite 242 Blue and if it needs to be broken the proper way is to heat up the joint with a hair dryer or industrial heat gun (best way) to about 300* until it lets go.

Staking is a positive way of retaining the nut and it is easy to see if the connection is failing. Given that the weapon may be used in a life threatening situation Loctite is not the bet way to deal with this issue in a serious use weapon.

 

[Bartholomew Roberts]

Not to mention that at least one reason manufacturers loctite the castle nut instead of staking it is because they may be using an inferior grade metal that is too brittle for staking. There are a couple of accounts of guys attempting to stake their receiver endplate and finding this out the hard way when the endplate shattered.

 

[Taurus 617 CCW]

That can also happen if the receiver end plate gets twisted along with the castle nut during disassembly. It' has happened to me a couple of times on guns with particularly difficult castle nuts.