Folks, it's been while that I was planning to install a rear sling mount and has always been hesitant to break that Colt's castle nut staking as I know I wouldn't be able to replicate it, plus I haven't removed one before.
I used a brownells M4 buttstock wrench as I read and received advices that a dedicated wrench will do a good job as compared to an AR15 combo wrench. Plus this brownells wrench is so robust machined from single piece .312" thick steel.
And its notches fills all 4 notches on the castle nut.
They key is to securely mount a vise on a bench and clamp the lower receiver as to how the army depot manual has stated. I refrained from using a magwell block as it would exert stress on the mag well during removal and torqueing which should be avoided. I had to remove the safety lever and if you noticed, the hammer was taken off too. As with Colt's, the hammer presses against the trigger and it causes tension on the safety lever. Even if I rotate it 45 degrees (between safe and semi), it still wouldn't come out of the receiver. I just clamped the lower just enough for the vise to hold it, NOT too tight.
After everything was snugged, I used a 24" breaker bar and the stakings on 2 points sheared off without hesitation. I didn't use a dead blow hammer to tap on the castle nut wrench, although it can be done as well.
Then I rotated back the castle nut. The challenge now is the staked endplate would not back out as well. This is due to its two staked points now presses hard against the buffer tube's threads.
I began to use a polymer flat head screw driver and started prying out below it going up. A regular flat head driver wrapped with cloth would do as well.
My goal here is to pry/lift the tab at the lower back of the end plate to clear the recess at the back of the receiver as I strike it with a rubber hammer.
Be careful no to lose the spring from rear take down pin.
Once the end plate is clear, start to loosen the buffer tube, but be mindful of the buffer retainer spring flying out. The buffer tube is now removed and the end plate is stucked tightly on the tube's thread.
I was told of two ways to remove it. One is using a wire cutter. I instead used the same castle nut wrench and turn it until the plate slides off forward the tube.
Yes, it will scratch/shear the tube's thread from its two staking points. But do not worry this will be under the receiver and nut and won't be noticeable.
I thought I wouldn't be able to reuse this same tube but after cleaning its threads with a brush, the same castle nut still threaded smoothly.
I began to apply aeroshell grease on the inside threads of the receiver, put the new rear sling mount and re-torqued @ 40 ft-lb.
I skipped staking it at this time and will put witness marks on it for now.
With the correct tools, I must say that I was able to reuse the same parts with little to very minimal scratch.
Even the notches on the castle nut was not dinged up during removal and after reinstallation.
Sorry for the few pics as I forgot to take some when I was at the middle of the challenging work.
Here's the finished job of the CQD rear-sling mount installed:
I used a brownells M4 buttstock wrench as I read and received advices that a dedicated wrench will do a good job as compared to an AR15 combo wrench. Plus this brownells wrench is so robust machined from single piece .312" thick steel.
And its notches fills all 4 notches on the castle nut.
They key is to securely mount a vise on a bench and clamp the lower receiver as to how the army depot manual has stated. I refrained from using a magwell block as it would exert stress on the mag well during removal and torqueing which should be avoided. I had to remove the safety lever and if you noticed, the hammer was taken off too. As with Colt's, the hammer presses against the trigger and it causes tension on the safety lever. Even if I rotate it 45 degrees (between safe and semi), it still wouldn't come out of the receiver. I just clamped the lower just enough for the vise to hold it, NOT too tight.
After everything was snugged, I used a 24" breaker bar and the stakings on 2 points sheared off without hesitation. I didn't use a dead blow hammer to tap on the castle nut wrench, although it can be done as well.
Then I rotated back the castle nut. The challenge now is the staked endplate would not back out as well. This is due to its two staked points now presses hard against the buffer tube's threads.
I began to use a polymer flat head screw driver and started prying out below it going up. A regular flat head driver wrapped with cloth would do as well.
My goal here is to pry/lift the tab at the lower back of the end plate to clear the recess at the back of the receiver as I strike it with a rubber hammer.
Be careful no to lose the spring from rear take down pin.
Once the end plate is clear, start to loosen the buffer tube, but be mindful of the buffer retainer spring flying out. The buffer tube is now removed and the end plate is stucked tightly on the tube's thread.
I was told of two ways to remove it. One is using a wire cutter. I instead used the same castle nut wrench and turn it until the plate slides off forward the tube.
Yes, it will scratch/shear the tube's thread from its two staking points. But do not worry this will be under the receiver and nut and won't be noticeable.
I thought I wouldn't be able to reuse this same tube but after cleaning its threads with a brush, the same castle nut still threaded smoothly.
I began to apply aeroshell grease on the inside threads of the receiver, put the new rear sling mount and re-torqued @ 40 ft-lb.
I skipped staking it at this time and will put witness marks on it for now.
With the correct tools, I must say that I was able to reuse the same parts with little to very minimal scratch.
Even the notches on the castle nut was not dinged up during removal and after reinstallation.
Sorry for the few pics as I forgot to take some when I was at the middle of the challenging work.
Here's the finished job of the CQD rear-sling mount installed:
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