I figured I'd compile a basic pictorial for the new users regarding the removal of the magazine tube to install a full length tube. I had snapped some photographs back when I did mine that might help some of the newer guys to get the job done.
This tutorial will span several posts due to the number of pictures posted limit that this forum has.
First, here is a schematic of the weapon we will be working on.
To begin, unload the weapon's chamber and empty the magazine. Field strip the weapon. Remove the trigger pack, bolt carrier group, barrel assembly and even the stock. You should be left with a receiver with its recoil extension and its magazine tube attached.
Now, disassemble the magazine tube #122. Unscrew the tube limiter. The tube limiter is not shown in the schematic. The factory bolt handle #39 can be used to pull the spring retainer cap #72 from the end of the magazine tube #122. You may also use snap ring pliers. Be careful when removing the spring retainer cap #72, the magazine spring #79 is under spring tension. Cup your hand over the end of the magazine tube #122 as you remove the spring retainer cap #72 to capture the magazine spring #79. Once the magazine spring #79 has been removed, tip the receiver downward to allow the magazine follower #76 out.
Now, I like to put my receiver in a vice to make the job much easier on myself. I used balsa wood strips this time between the receiver and the vice. I avoided using a rag because I was worried that it might start a fire when heating the receiver.
This was probably overkill since the heat stays pretty localized to the area of the receiver with the threads in it. The rest of the receiver will get hot, but nowhere near the temperature required to start a fire.
You do not want to squeeze the receiver very tight. Aluminum receivers can twist rather easily. If done right, you won't be applying much torque to remove the magazine tube anyway.
I flushed out the receiver with BreakFree Powder Blast solvent to remove much of the oil inside the receiver. My concern was that it might start smoking during the heating process.
At this point, I reinstalled the trigger pack and the bolt carrier group. The reasoning was the trigger pack might add some rigidity to the receiver. Having the bolt carrier group present won't hurt, but probably won't help much either honestly in hindsight.