870 Mag Extension Tube Broke!

[Homerboy]

I take my 870 with the factory installed mag extension to the range today. Load up and fire one shot. SPROING!! The mag spring flys out of the gun! The piece that you turn to tighten the tube from the mag is still clamped to the tube, but the extension moved forward and was completely apart from the piece. I was able to re-screw it back on, and it did it again! I re-screwed it again and finished out the session. Why would they make it so it screws on BOTH ends? Why not have the end attached to the extesnion be permanent? I guess I had it screwed too much on the top and only one or two turns onto the mag tube or something, but I think I'm gonna be ordering a magazine cap and new spring and go back to the standard configuration. How many shells does a standard 870 hold in the tube, 4? I'd rather have 4 that I know work than 6 that may.

 

[Badger Arms]

Somebody somewhere installed it wrong. The reason that both are threaded, I believe, is to allow you to remove the barrel from the shotgun without having to take the clamp off the mag tube. You should be able to unscrew just the nut and pull the whole barrel assembly with extension attatched off the front of the gun. I could be wrong as I've never seen it done.

 

[Homerboy]

Yeah, that's how I always removed it to clean the gun. Unscrew the nut, and lift the extension still attached to the barrel off the tube. To reinstall, I just rescrewed it in. I must have taken that thing apart 100 times and it never did this. What is the benefit to being able to remove the nut from the extension?

It's not sitting well with me at all.

 

[MAX100]

Operator error, it's not the tube design. Use the factory mag tube clamp or a good after market one.

I do prefer a one piece tube over the two piece tubes.


GC

 

[Homerboy]

I am using the factory mag clamp. I've never taken that off or even loosened it. The extension stayed attached to the barrel with the mag clamp, but it punched forward abit off the mag tube, so the nut that you spin to tighten the extension to the tube was still on the mag tube, and the extension was apart from it. it is all factory and I've never changed anythign.

 

[MAX100]

No biggie! Just tighten the tube in the base properly.


GC

 

[Homerboy]

I appreciate your help, but is it that simple? The mag tube was on securely when I last took it apart last week. When I rescrewed it on after the first incident, I tugged pn it before I fired, but it happened again. The nut on the extension stayed on the magazine tube, and the extension shifted forward so that it extended past the barrel. How do I make sure that the clamp will not seperate from the extension again?

 

[Fred Fuller]

If the clamp doesn't move on the barrel, the extension tube shouldn't be able to move in the clamp- the machine screw that holds the clamp tight goes through a notch in the extension tube. That screw should help fix the tube in place.

Keep in mind, Remington's magazine extension was originally designed as part of a system to allow mounting a bayonet on the gun in the old 'trench gun' format. Remington's Military and Police Shotgun Development Program grew out of US involvement in the war in Southeast Asia and began in the early 1960s. Early 870s prototyped in this program had fixed 6 or 7-round magazines and used the same style of bayonet adapter/heat shield used on earlier trench guns.

By 1967 Remington had decided that separate magazine extensions were a better option, and in 1969 the patent on what would become the system used in the Remington 870 Mark I Military came through (Pat # 3,445,951). The prototypes had a perforated steel handguard that was dropped on later production models ( http://www.olive-drab.com/gallery/photos/m870_shotgun_01_500.jpg ).

The reason for the odd extension on the front of Remington factory magazine extensions was that it served as a place for the ring on the standard M7 bayonet- the bayonet lug was on the bottom of the clamshell reinforcement that stabilized the barrel and the magazine extension (see the picture above). Later developments in the M&P Shotgun Program, aimed at law enforcement, replaced the clamshell clamp with the narrow band type barrel clamp we see now. The same style magazine extensions were used throughout the program and are still produced to this day. Properly assembled, they still work very well.

lpl

 

[Hungry Seagull]

The factory clamp on my mag tube stays as it is. It is reinforced by another clamp holding the light near it.

I never touch the tube or it's screw. I do check it to be sure it's secure.

Mr Lee Lapin, Your knowledge of this Gun and the history humbles me. Im most appreciate your lesson regarding that tube. I was beginning to wonder.

But now I see it. Thank you.

 

[Fred Fuller]

HS,

It ain't me- I cheat 8^). That info is courtesy, as is often the case, of Thomas F. Swearengen's classic reference, The World's Fighting Shotguns (c 1978).

lpl

 

[Badger Arms]

Google Patents: http://www.google.com/patents?id=9CMbAAAAEBAJ&printsec=drawing&zoom=4&dq=3,445,951#PPA2,M1

It's interesting, I qualified with these shotguns. We shot high-brass 9-pellet loads at an indoor range. 10 rounds to qualify. The guns were quite worn but still operated well. We'd take them out and shoot about 20 or so "cracker shells" a day for months during the summer scaring the Geese and Ducks. Probably about ten steel-shot shells a day also for the Stuburn Geese and Ducks. Cleaned twice a day at the end of each shift with Rem-oil. These were working guns. They eventually swapped the ones with the mag extensions out for slug-barrels to use against the Bear and Moose problems we had on base. Don't know what happened to the extensions, but all three that I saw were broke with missing beads, stripped threads on the screws, bent, dented, etc.