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  • amoebicmagician

    Samopal Goblin
    Dec 26, 2012
    4,174
    Columbia, MD
    STAKE YOUR CASTLE NUTS!

    while under extended an tough use I've had a castle nut or two back off a bit. Not enough to be troublesome, but the nut DID back off on a few Aluminum lowers. For the most part though, for an aluminum lower, torquing to 45 lbs works great for normal use.

    HOWEVER

    Ever since my first polymer lower build I have been plagued with problems of the castle nut backing off with not very strenuous use.

    This varies from lower to lower- some of them hold up almost as good as a aluminum lower in pracitce, but then when you go to undo the nut, it takes next to no force to crack it loose. I believe these differences are in how rigid the polymer making up the receiver is, as the more rigid it is, the longer the nut stays in place.

    So, being as I didn't know how and was afraid to mar my rifles, I did not stake my castle nuts, however, after repeatedly finding my castle nut loose on that first problem poly lower I mentioned, sometimes even just from sitting in the safe with no use, I decided I had to do something.

    I didn't even have to ask, Chad volunteered the info I needed, and not only was it so concise I couldn't mess it up, he DIRECTLY LINKED ME TO THE TOOLS I WOULD NEED FOR 1/5th the cost of getting them at home depot.

    so, it ended up being that for the cost of 6 bucks for a self propelled staking punch, and 25 bucks for a new BCM buffer tube, and I was able to do a few things:
    Number one, follow Chad's advice to torque slightly over 40 lbs and then follow the procedure he laid out for me I was able to get that trouble lower torqued and staked.
    Number Two, I was able to stake all the builds I've done, and my brother has done, for a bit more piece of mind.
    Number 3, I was finally able to remove some of my factory hardware from a few of my rifles, and replace them with the stuff I really wanted on there, which I could not do before because I did not want to destroy the staking thinking I could never re-apply it myself.


    So, fast forward a bit, and I have taken the jiggly polymer lower to the range and shot the crap out of it. Took it home, not only no loosening, but no movement of any kind. Took her out again today, same deal (it's cold as crap today, I think it may have been a mistake to go) and ran 200 rounds of cheap steel cased wolf through the rifle. Took back home, and same deal. No movement at all, so just experimentally I attempted to lightly see if the nut would break loose, as I have seen that sybdrome before, where even though they are nominally in place, they are in fact able to be broken loose with little more than hand pressure.

    No go. That castle nut is no goin ANYWERE.

    I've been asked before why I even bother using that lower if it's so wiggly.

    Well, it is also INCREDIBLY strong. After realizing it had issues I tried to break it on two separate occaisions. Once jumping off the couch onto it, and the second time trying to break it like kindly over my knee. I could't even mar it. There is also the fact that it is slightly over size, so that it's flexy nature allows me to exert a little force and put the pins through, leaving no room between upper and lower, with NO side to side movement. I have gotten excellent accuracy out of this lower with good uppers on it. Now I can really trust it.

    I have also now staked the rest of my builds, double staking the polymer ones, and they all came out professional looking and functional following Clandestine's advice.


    So yeah, PSA:

    Stake those castle nuts on your polymer lowers
     

    zombiehunter

    Ultimate Member
    Jul 8, 2008
    6,505
    So...share the how to and link to tools? I've noticed the same issues with my ARs. Guess I never torqued them down enough to begin with.
     

    amoebicmagician

    Samopal Goblin
    Dec 26, 2012
    4,174
    Columbia, MD
    Good, I almost took the polymer route but was never confident. ARs are not like socks--get good ones if you only have a few.

    actually, other than the castle nut issue, my polymer lowers have been fantastic- although I have never bought one that wasn't media reinforced.

    But yeah, polyamide and decent polymer receivers work great other than the castle nut issue. Just make sure it is a quality polymer.

    As for links:
    http://www.amazon.com/gp/product/B0037UUO60/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

    This center punch has a spring in it, and works great.

    I also picked up a husky and a general brand one from home depot, but they do not seem to be quite as good, as well as costing a bit more.

    Just attach the plate and castle nut as usual after installing the buffer tube into the threads until the retainer for the buffer is retained, then torque to 42 lbs on your torque wrench. Some people recommend 40, I usually do 45. You can use or not use blue loctite, I have found that it does not seem necessary when staking the castle nut.

    If you do not have a torque wrench you can just tighten it down good and tight, I did this on my first few builds and it worked fine even without staking and loctite.

    Anyways, follow this tutorial for staking procedure, but it is NOT hard. Just make sure to get a good divit going STRAIGHT DOWN before your start angling it into the slot on the castle nut.
    https://www.youtube.com/watch?v=aCWDT1B_EIk

    But yeah, I am a fan of polymer receivers. I was iffy until I tried my damndest to break one and couldn't- now that I've got the castle nut issue taken care of, I am a happy camper.

    I do NOT, however, under ANY CIRCUMSTANCES, recommend a polymer buffer tube. Haven't seen a single one that worked worth a damn. And not because they were fragile.

    I've also had good success making a line of peened material from castle nut to retaining plate for extra security, but I don't think it was necessary, as even the poly lower I was having the most trouble with has not shown the need for any but the regular staking
     

    INMY01TA

    Ultimate Member
    Dec 29, 2008
    5,816
    I've found on normal lowers staking isn't necesary when using blue loctite.
     

    Sticky

    Beware of Dog
    MDS Supporter
    Mar 16, 2013
    4,501
    AA Co
    So...share the how to and link to tools? I've noticed the same issues with my ARs. Guess I never torqued them down enough to begin with.
    Ideally, be sure your castle nut has the little notches on the front edge, where it marries against the endplate... some do not.

    Simply use a center punch (I use a spring loaded one) and dimple the endplate directly opposed to the small notches (there are usually 3). I do all three in most cases as insurance..

    This is not one of my better ones, but.. I had the gun out for other reasons, so.... here is what it looks like, sorta..

    011139e737479100931047bf7ee9cb658f6620051a%20618x800_zpsefl09mgo.jpg
     

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