I'm offering this up as a step-by-step guide to a solution I cooked up for M4 stocks. What each person chooses to do, from simply throwing a screw in it, or epoxy glue, is up to them- however, I am posting this because I believe it has several advantages:
1) Removal of the screw will NOT allow the stock to be collapsed or extended. This is because the plunger is still locked in place by spring pressure.
2) Not relying on super glue or epoxy means it can't be shocked loose (slamming trhe rifle butt on a table will not make it into a "collapsible stock".
3) We have seen a wave of prosecutions over "evil features" including a video released by Nassau DA's office that was edited to appear to incriminate the defendants. This gives me (and should give all of us) very little faith that our "pinned" stocks that can get the pins pushed or tapped out offer us protection under the current administration's interpretation of the law.
4) This can be disassembled and replaced without destroying the buffer tube. Removing the buffer and drillling a small (1/16") hole in the top of the buffer tube allows a wire to be inserted to depress the plunger from the top and allow disassembly of the stock.
OK so without further ado, this is the method I came up with, step-by-step:
Pictured above are the original components of the factory stock, disassembled. In addition to the activation lever there is a plunger, a spring, a bushing, and a pin.
The bushing and pin will go in the spare parts box, we will be substituting a 1/4x20 hex head stainless steel machine screw.
Assemble the stock and measure how far the threaded part of the plunger protrudes from the stock.
This one extends 6.64mm.
Measure the length of the shank of the machine screw.
I got 16.18mm
Time for some rudimentary mathematics:
(length of stock plunger) - ( length of plunger 'stickout' + length of machine screw shank) = length to cut plunger.
Mark and cut off plunger, dress end square with a file.
Here are the modified plunger, the spring, and the machine screw. The section that got cut off the plunger gets thrown away.
Use a soda straw to hold the spring and plunger assembly together so you can insert it into the stock from the top.
You need to "block off" all of the holes REARWARD of the position you want the stock to be "fixed" in. This keeps the plunger from snapping into the wrong hole. I used aluminum duct tape wadded up in the hole with another couple pieces over the top.
use a screwdriver from the top of the stock to depress the plunger and slide the stock onto the buffer tube. when it gets to the first available hole that you have not plugged, the plunger will snap into place. The stock is now a fixed, non-telescoping stock.
Here is the spring from the bottom, there is no longer any way to retract the spring since we cut the bushing end off of the plunger.
BUT for the sake of cosmetics, we want to attach the lever back. This is where the 1/4" machine screw comes in.
You can thread the stock hole for 1/4"x20 thread, or you may be able to simply screw the machine screw into place with a little muscle if you don't have a tap- it's only going into plastic.
That's it! Hope this was helpful!
Also, because I don't know where to put it:
This is an "evil feature" A2 flash hider...
you can use this YHM comp and drill at the location shown, then insert the back of the drill bit, cut it off with a Dremel, and weld into place. Drill rod is hardened steel, trying to muscle it off with a wrench will surely remove the "evil" threads from the soft barrel. This is really about all most of us can do on a stainless barrel. I used two pins.