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Author Topic: Unscrewing barrel from barrel trunnion  (Read 4626 times)

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Offline jamesavery22

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Unscrewing barrel from barrel trunnion
« on: September 17, 2016, 04:12:17 PM »
Has anyone gotten these two apart?  I tried heating it with the heat gun. There's definitely some kind of thread locker in there. It pushed out once it got to around 375F.  Are the threads RH? I haven't gotten it to budge at all... Any suggestions?
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Offline Tenbones

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Re: Unscrewing barrel from barrel trunnion
« Reply #1 on: September 17, 2016, 04:41:00 PM »
Can I ask why you want to separate the two?  The reason I ask is, short of putting on a different barrel it's not worth the hassle separating the two.

Here's a link to an earlier discussion:    http://www.czfirearms.us/index.php?topic=77844.0
« Last Edit: September 17, 2016, 04:57:06 PM by Tenbones »
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Offline Border Dave

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Re: Unscrewing barrel from barrel trunnion
« Reply #2 on: September 17, 2016, 09:50:18 PM »
This is an interesting thread.  When I took my barrel off to send it out for re-threading, the trunnion literally fell apart from around the barrel.  Mine does't have any threads holding it in.
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Offline jamesavery22

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Re: Unscrewing barrel from barrel trunnion
« Reply #3 on: September 18, 2016, 03:43:38 PM »
Emailed Cz USA. Will post here whatever reply I get. I too am shortening and threading the barrel. I think I can do it without removing the trunnion. It'd just be easier without the trunnion...
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Offline jamesavery22

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Re: Unscrewing barrel from barrel trunnion
« Reply #4 on: October 16, 2016, 02:37:56 PM »
Finally got this taken care of.  CZ's reply wasn't super helpful.  They said it has thread locker on the threads and a lot of torque was applied...
This is what I did.  Heated up the threaded area to 380ish?  Supported the trunnion in a vice and the barrel with a block of wood with a hole through it.  Had to put the open ended wrench in a pipe to get enough leverage.  Marred up the wrench cuts in the barrel a little.  It looks like it'll be fine.

« Last Edit: October 16, 2016, 02:46:16 PM by jamesavery22 »
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Offline mursalot

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Re: Unscrewing barrel from barrel trunnion
« Reply #5 on: October 16, 2016, 04:58:41 PM »
Nice work and thank you for the pic! I think you're the first one to go into detail and post a pic of this. At least now you don't have to worry about 922r compliance since the carbine already has the necessary USA parts

As a side note, I remember reading that torque specs for the barrel nut was 70 INCH pounds (that's like 5 foot pounds) and the screws keeping the clamshell receiver together are 17 INCH pounds (about 1? foot pounds). I understand why they use loctite on everything.

I'm also remember reading that the red loctite doesn't melt until 500?F
« Last Edit: October 16, 2016, 05:07:14 PM by mursalot »
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"click" when you expect it to go "bang" and

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Offline jamesavery22

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Re: Unscrewing barrel from barrel trunnion
« Reply #6 on: October 16, 2016, 05:31:14 PM »
Thanks.  Whatever they used on the barrel threads on the trunnion didn't seem like loctite.  Red or blue.  Red loctite was definitely used on the muzzle end for the fake suppressor.  The thread locker they used on the barrel was more white.  When hot, consistency was different from loctite.  Some of it bubbled out through the super thin space between the barrel and the trunnion at the bore end.  Believe there was some grease in there as well. When the threads finally cracked open there was a puff of steam that came out.  Whatever locker they used loosened up before 400?.  Just glad that's done with. Time to focus on modifying the handguard and how it mounts...
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Offline akuser47

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Re: Unscrewing barrel from barrel trunnion
« Reply #7 on: October 16, 2016, 07:03:49 PM »
Nice work
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Offline Sigm4

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Re: Unscrewing barrel from barrel trunnion
« Reply #8 on: October 17, 2016, 06:41:07 PM »
Was your barrel staked into the trunion/fixation?  I can't recall off hand but I seem to remember my carbine barrel being staked when I had it apart. I'm planning on staking my CZ Custom barrel into the spare fixation I purchased in order to SBR the gun.
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Offline mursalot

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Re: Unscrewing barrel from barrel trunnion
« Reply #9 on: October 17, 2016, 08:40:15 PM »
Quote from: Sigm4 on October 17, 2016, 06:41:07 PM
Was your barrel staked into the trunion/fixation?  I can't recall off hand but I seem to remember my carbine barrel being staked when I had it apart. I'm planning on staking my CZ Custom barrel into the spare fixation I purchased in order to SBR the gun.

good question.  i remember posting about this in another thread.  the barrel is torqued to a certain spec (wish i knew how much) and then it's staked.  kinda like the screws that secure the gas key to the bolt carried on an ar15
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2 things you never want to hear when you pull the trigger:

"click" when you expect it to go "bang" and

"bang" when you expect it to go "click"

Offline jamesavery22

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Re: Unscrewing barrel from barrel trunnion
« Reply #10 on: October 25, 2016, 10:49:16 AM »
+1 for what John said. There were marks on the trunnion and barrel. Not truly staked though.  I filed them down just to be sure before applying any torque. The amount of material needed to be removed to remove the marks was too little to be of any consequence.
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Offline Tad_07

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Re: Unscrewing barrel from barrel trunnion
« Reply #11 on: October 27, 2016, 07:39:07 PM »
Quote from: jamesavery22 on October 25, 2016, 10:49:16 AM
+1 for what John said. There were marks on the trunnion and barrel. Not truly staked though.  I filed them down just to be sure before applying any torque. The amount of material needed to be removed to remove the marks was too little to be of any consequence.
Nice to see you on this board too. Still love the ak-acr setups you did....and your nice sagia folder conversion.
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