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Posted: 12/19/2020 11:28:44 AM EST
[Last Edit: 12/19/2020 11:30:56 AM EST by quercusalba7]
First time builder here. I accidently cracked a castle nut while putting together my first lower. I believe I over torqued the castle nut by having my torque wrench lined up with my castle nut wrench. I have since read that it should be about 90 degree in relation to the castle nut wrench to get the actual set torque. Or maybe the castle nut was bad or a combination of both.

Anyway, I'm worried that I may have damaged the lower. It looks fine. Threads where the extension screws in are fine. Lower doesn't look bent/misshapen in any way, but if I applied enough force to break the castle nut clean threw, I'm worried I bent the lower in some way. Is there a way to make sure the lower is still okay? Is the lower probably still GTG? The lower is Aero Precision M4E1.

Thanks for any help.
Link Posted: 12/19/2020 11:38:16 AM EST
The threads on your tube would likely yield long before an issue with your receiver.

Buy a quality castle nut for replacement and inspect tube threads.
Link Posted: 12/19/2020 11:39:34 AM EST
[Last Edit: 12/19/2020 11:40:17 AM EST by s4s4u]
Probably just a crap castle nut.  If the threads are okay I highly doubt there is any damage to the lower itself, depending on how you held it.  There is no need to torque the shit out of a castle nut.  Shit, I hold the lower in my hand the the stock between my legs.  Stake it and it ain't going anywhere.
Link Posted: 12/19/2020 11:54:13 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By s4s4u:
There is no need to torque the shit out of a castle nut.
View Quote

This
Link Posted: 12/19/2020 11:54:46 AM EST
If you could tell us the source(seller/brand) for the castle nut, that would really appreciated.

Short of a bad batch of heat treatment, it's pretty hard to think that a steel castle nut would crack before it simply deformed/rounded out the notch.

Can you share a photo as well?
Link Posted: 12/19/2020 12:01:00 PM EST
Thanks for the replies! I appreciate the help. I'll take a closer look at the threads and make sure they look ok. I had the lower on vise block when I torqued it down.
Link Posted: 12/19/2020 12:13:38 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Wangstang:
If you could tell us the source(seller/brand) for the castle nut, that would really appreciated.

Short of a bad batch of heat treatment, it's pretty hard to think that a steel castle nut would crack before it simply deformed/rounded out the notch.

Can you share a photo as well?
View Quote


The castle nut was Aero Precision. It was included with an Aero Precision buffer tube kit I bought for the build.

I should have taken a picture or kept it, but I already tossed it. The castle nut snapped and broke at one of the notches.
Link Posted: 12/19/2020 12:34:36 PM EST
[Last Edit: 12/19/2020 12:37:36 PM EST by jgreen2193]
happened to me before.
i greased my threads, installed my tube, properly torqued castle nut the right way, 90* 40ftlbs, i couldnt remove it when i tried to, not staked. used 3 different wrenches and they all slipped. held square etc. im very mechanically inclined.
name brand nut too.
couldnt get it off.
so, i used an 18" pipe wrench, the nut cracked in half and fell off as i loosened it. no damage to receiver. some the threads were gouged on the extension tube.
i wouldnt worry about the threads on the extension tube its fine. but do you personally want gauged up parts on your gun if you dont have to?

i always clamp the tube in the vise when torquing the nut down, i dont like the flex and stress on the receiver using a magwell block.
Link Posted: 12/19/2020 1:05:51 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jgreen2193:
happened to me before.
i greased my threads, installed my tube, properly torqued castle nut the right way, 90* 40ftlbs, i couldnt remove it when i tried to, not staked. used 3 different wrenches and they all slipped. held square etc. im very mechanically inclined.
name brand nut too.
couldnt get it off.
so, i used an 18" pipe wrench, the nut cracked in half and fell off as i loosened it. no damage to receiver. some the threads were gouged on the extension tube.
i wouldnt worry about the threads on the extension tube its fine. but do you personally want gauged up parts on your gun if you dont have to?

i always clamp the tube in the vise when torquing the nut down, i dont like the flex and stress on the receiver using a magwell block.
View Quote


The flex/stress on the receiver was what had me worried. I bought a new extension tube already, but I was less than impressed with the castle nut that came with the replacement Aero buffer kit I ordered. The staking notches looked terrible to me, so I ended up spending & ordering a couple Forward Controls Designs castle nuts which look great.
Link Posted: 12/20/2020 6:35:37 PM EST
[Last Edit: 12/20/2020 6:38:39 PM EST by 556Cliff]
Interesting... This castle nut was possibly from Aero Precision too.

Link Posted: 12/20/2020 7:44:34 PM EST
If you are getting s replacement forward control design makes a good one.

https://www.forwardcontrolsdesign.com/CNF-Castle-Nut-Forward-Controls_p_103.html
Link Posted: 12/20/2020 8:08:56 PM EST
[Last Edit: 12/20/2020 8:10:38 PM EST by AlterEgo2]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jgreen2193:
happened to me before.
i greased my threads, installed my tube, properly torqued castle nut the right way, 90* 40ftlbs, i couldnt remove it when i tried to, not staked. used 3 different wrenches and they all slipped. held square etc. im very mechanically inclined.
name brand nut too.
couldnt get it off.
so, i used an 18" pipe wrench, the nut cracked in half and fell off as i loosened it. no damage to receiver. some the threads were gouged on the extension tube.
i wouldnt worry about the threads on the extension tube its fine. but do you personally want gauged up parts on your gun if you dont have to?

i always clamp the tube in the vise when torquing the nut down, i dont like the flex and stress on the receiver using a magwell block.
View Quote

It probably galled over a few threads while going on, which is like x-threading.

I think it's important for people to check the threadings using a thread gauge before installing the parts. You'd be surprised what you find.
Also good to just check how loose or tight the nut is on the buffer tube. If it wobbles around when threaded on, that's not good. This fitment should be fairly wobble free.

I most of the time use the DoubleStar thin lock rings, 1st one snuggly, and a 2nd as a locking nut. Then no need to stake it. Never had an issue.
Link Posted: 12/21/2020 9:13:33 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By everready73:
If you are getting s replacement forward control design makes a good one.

https://www.forwardcontrolsdesign.com/CNF-Castle-Nut-Forward-Controls_p_103.html
View Quote


That's good to hear. I bought a few of those to try.
Link Posted: 12/21/2020 9:20:04 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 556Cliff:
Interesting... This castle nut was possibly from Aero Precision too.

https://www.youtube.com/watch?v=t9GHDAmK24I
View Quote


Sounds familiar. Heard a popping noise and the nut split at one of the notches, although it didn't split into two pieces. I really wish I'd taken a picture of it.
Link Posted: 12/21/2020 10:26:24 AM EST
yeah i just happen to catch that SOTAR video this morning and definitely not something that's usual.  I suspect a bad batch.

The Forward Controls one is solid
Link Posted: 1/13/2021 1:50:25 PM EST
[Last Edit: 1/13/2021 1:59:30 PM EST by E_E]
Broke one too. Only my second "build" so maybe it was my fault but I think it was a cheap part.



The part came in a buffer kit from Kaw Valley and had all 5 star reviews on the website I ordered it from.
item on wing tactical

I used a real avid armorers wrench and didn't even seem to crank it too hard. I had just installed a spikes tactical castle nut on a different lower using the same wrench and it went on fine and luckily had a second ST nut to use as a replacement for the Kaw valley one I just broke. Im assuming that is a cheap castle nut with that granular looking metal on the broken edge. Is that a cast piece then? Just starting out in the AR building world.
Link Posted: 1/13/2021 2:19:09 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By berkeleygiraffe:
yeah i just happen to catch that SOTAR video this morning and definitely not something that's usual.  I suspect a bad batch.

The Forward Controls one is solid
View Quote

I believe Chad from SOTAR helped design the FCD castle nut
Link Posted: 1/13/2021 2:20:37 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By E_E:
Broke one too. Only my second "build" so maybe it was my fault but I think it was a cheap part.

https://drive.google.com/uc?export=view&id=1_yNkepN_Z5pQRPBs9M07gvbMFz3ba56Z

The part came in a buffer kit from Kaw Valley and had all 5 star reviews on the website I ordered it from.
item on wing tactical

I used a real avid armorers wrench and didn't even seem to crank it too hard. I had just installed a spikes tactical castle nut on a different lower using the same wrench and it went on fine and luckily had a second ST nut to use as a replacement for the Kaw valley one I just broke. Im assuming that is a cheap castle nut with that granular looking metal on the broken edge. Is that a cast piece then? Just starting out in the AR building world.
View Quote

That looks MIM or cast.
Link Posted: 1/13/2021 8:36:21 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Tigwelder1971:

That looks MIM or cast.
View Quote

Cast shouldn't look grainy like that. The uniform look inside and out of that nut makes me think polymer of some sort. If it's metal and heat treated, it looking like that is a sign that the metal was burned before the quench and instead of hardening the metal, made it weak and brittle.
Link Posted: 1/13/2021 9:36:00 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gjones80:

Cast shouldn't look grainy like that. The uniform look inside and out of that nut makes me think polymer of some sort. If it's metal and heat treated, it looking like that is a sign that the metal was burned before the quench and instead of hardening the metal, made it weak and brittle.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gjones80:
Originally Posted By Tigwelder1971:

That looks MIM or cast.

Cast shouldn't look grainy like that. The uniform look inside and out of that nut makes me think polymer of some sort. If it's metal and heat treated, it looking like that is a sign that the metal was burned before the quench and instead of hardening the metal, made it weak and brittle.


The entire thing is magnetic, so guessing its all metal but not sure how it was made. Didn't seem to be too strong.!
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