Benelli M4 -- Magazine Tube Removal Pictorial

[StrangerDanger]

Hi all:
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.

[StrangerDanger]

Now, get out your heatgun. I bought a cheap unit from Home Depot. It is a 1000 watts and does the job very well. It actually was enough to remove the receiver extension from my M4.



You want to apply your heat at the base of the magazine tube #122 and on the aluminum receiver. The heat will penetrate into the threaded area of the receiver and begin breaking down the factory locktite. How long you will have to apply heat will depend on how much locktite put on your weapon and how strong of a heatgun you have. Typically, it takes about ten minutes before you will see the area around the magazine tube and receiver start to smoke. This smoke is the locktite melting and burning off.

You should twist from the end of the magazine tube. The tube will be warm, but shouldn't be too hot to touch.

Attempt to twist the magazine tube from the receiver every few minutes. You do not need a lot of strength. The goal is to break the locktites bond, and the tube will simply unscrew with very little effort. If it still won't budge, keep applying heat in five minute intervals. Do not use a strap wrench. You will be applying a dangerous amount of torque with it.

In the multiple M4's I've done, the tube will slowly start to untwist like if you were twisting through thick glue. Usually it will stop turning after about 1/16 of a full rotation. So keep applying heat. This will repeat itself several times before the tube will finally fully unscrew.

[StrangerDanger]

As you can see, the receiver will look nasty once you get the magazine tube removed. The white powder is the pulverized locktite. Flush the receiver out with BreakFree to remove the bulk of the debris. Use acetone and a wire brush to remove the remaining locktite from the receiver threads.



Here is the magazine tube #122 removed from the receiver. You need to recover the Forearm Retaining Band #69 (gigity). The Forearm Retaining Band #69 is a slip fit part that will simply pull off of the Magazine Tube #122.

[StrangerDanger]

Front face of the Forearm Retaining Band #69


Rear face of the Forearm Retaining Band #69

Note the raised portions on the Forearm Retaining Band #69. They interface with the front of the receiver. They act as a locator and to reduce movement.

[StrangerDanger]

Once you've cleaned up all the locktite from the receiver, it should look like this.

[StrangerDanger]

Now that the removal is complete, it is time to reinstall your new full length magazine tube. Test fit your magazine tube into the receiver. Make sure that the threads are clean and they do not hang up during seating. You may reapply locktite to your new magazine tube if you wish. I personally forgo this option so I can clean the weapon better. I simply tighten the tube down very tight by hand. It is much easier to clean the receiver if you can remove the magazine tube.

Once you have tightened your new full length magazine tube. Insert your follower down the magazine tube. Then install your magazine spring. Then compress the magazine spring, and install the Magazine Spring Retaining Cap. This is best to do with snap ring pliers.

Reassemble your weapon and function test it. Ensure that the weapon can now seat seven 2 3/4" shells or six 3" shells in the magazine tube.

All in all, this job sounds harder to do than it really is.

[StrangerDanger]

Now for some full length magazine tube porn. This is a carriercomp titanium magazine tube. I had a factory Benelli extension previously, it sucked dong compared to the full length tube. It was heavier. Not 922 compliant. Finish was terrible. It would loosen during shooting sometimes. Harder to install the spring with the extension since the spring would hang on the joint between the two tubes. The factory extension was expensive too. I bought mine for 70 dollars new back in 2004. I sold it used in 2009 for 150 dollars.


Factory Benelli Extension


Carriercomp Titanium full length Magazine Tube.

[StrangerDanger]

[Unobtanium]

Awesome pictorial, but it might scare some people.

2 hot-pads on either side of the reciever, hold it between your knees, heat the mag-tube at the base and the part of the reciever that is directly holding it, and twist the mag-tube free with your hands. Put some CLP inside the mag-tube at the base, and when it starts to smoke out of the tube, you have it hot enough. Twist it as much as you can, re-heat, repeat.

Tutorial above is very good, but don't let it intimidate you. The above few lines sum the operation up. It's what I do when they CAKE! the lok-tite junk they use on there. If they only use a little bit, I will just glare at it for a few minutes and it un-screws with ease.

[Bello]

good job on that stranger. unobtanium you must have had a ridiculous heat gun i had a 1200 and i heated the base of the tube at least 20 minutes and it never turned i then i gave up and heated the receiver for about 5 all over and it just almost twisted out like butter..