Browning Auto-5 Sheared Magazine Tube Removal

Browning Auto-5 Sheared Magazine Tube Removal

In the short time we’ve had our Pro Shop open, we’ve had some fairly major repairs walk in.  This is one of them.  A Browning Auto-5 that had its magazine sheared off inside the receiver!

For reference purposes, a schematic of the Auto-5 can be found here.  

Here it is!  Notice the magazine tube sheared off about .200″ below the surface.  Some shotguns, like the Browning have magazine tubes that are threaded to the receiver, these can be swapped out if needed.  Others, like the Remington 870 are brazed and not easy (or possible) to change at most shops.  Since this was threaded and we like a challenge, I gave it a whirl.

Before we get to work, let’s take a look at the site disclaimer:

The contents of are produced for informational purposes only and should be performed by competent gunsmiths only. and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.

Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.

Modifications to a firearm may result in personal injury or death, cause the firearm to not function properly, or malfunction, and cause the firearm to become unsafe.

The Auto-5 magazine tube is retained with a screw through the side of the receiver; this needs to be removed prior to attempting to unscrew the magazine tube.  After that, I tried to unscrew the broken off piece with a pair of pliers, and then used a punch.  It didn’t move, so now I need to machine it out.  I suppose you could grind it out with a Dremel, however, I am unsure how you’d do so and avoid damage to the receiver.

I went ahead and “fixtured” up the receiver on the milling machine. I used an angle plate secured in my vise.  The receiver is clamped to the plate.  Note that the drive spring tube that cannot be easily removed from the action.  This type of set up takes a lot of time to figure out.

A view of the other side of the set up.  Note the 10 mil tape (available at Brownells) between the action and angle plate, this protects the receiver from damage.  Since the top of the receiver has a radius, that is pushed off the back of the angle plate.

After indicating the center of the hole, I ran a helical milling cycle on my Haas CNC mill to remove the center of the magazine tube.  It machined the minor diameter of the threads on the replacement magazine tube.  If you only had access to a regular milling machine, a boring bar would work just as well.  Bear in mind that the tube is approximately .995″ in diameter and the minor diameter of the threads are approximately .955″.  The tube is thin and the set up must be precise.

If you look where I was machining, you’ll notice metal threads on the bottom left side of the hole.

I peeled away the threads with pliers.  Eventually I was able to unscrew what was left of the old magazine tube.

Finally! I installed the new magazine tube and reassembled the gun!