View Full Version : 870 Mag Extension

AR Man
September 22, 1999, 06:54 PM
I am mounting a mag extension tube on my 870 and I know the little interior "bumps" in the standard tube have to come out. Has anybody taken these out? Suggestions? Ideas? Take it to a gunsmith? I am fairly good mechanicaly so if it is not to involved I will do it my self.

Second, the standard mag plug uses these small bumbs as a retainer is there problems using the standard plug and spring after they are gone? I want to be able to use the shotgun interchangeably for hunting and defense.

[This message has been edited by AR Man (edited September 22, 1999).]

September 22, 1999, 08:29 PM
The quickest way is to just drill them out, I think a 3/16 will do the job, then smooth the edges with a Dremel or file.

September 22, 1999, 11:15 PM
The quick easy way is to drill out the dents. This will leave you with two holes in your mag tube. They are hidden under the barrel collar, so it isn't so bad. Just make sure to keep any grit or water that may sneak in during use, cleaned out. Don't forget to de-burr the holes to prevent the shell rims from snagging.

The best way to get rid of the dents is to use a shotgun magazine dent raiser. It will press the endents flush with the rest of the tube. Its a real quick procedure. Your local gunsmith should have the tool to do it. Otherwise it'll cost you about $45 from Brownells (Part# 080-870-206).


September 23, 1999, 03:29 AM
My way take a little more work but if you have a Dremel Tool. who doesn't nowadays?
Put an abrasive stone in your Dremel and grind the dents down until they are flat if you are carefull you will still some material
left over that is fairly thin. You will not have 2 holes in you magazine tube. Then take some fine emery clothe and polish the the area where the dents used to be. Assemble the tube and make sure that there is no binding of the spring. If there is you may need to take off a little more metal and polish again. You should be able to do this in about 20 minutes. So it is not real time consuming.

September 22, 2000, 05:53 PM
Okay, I have a question. Once the indentations are drilled/flattened out, does that mean one cannot revert back to the standard magazine (without the extension)? I was thinking that it wouldn't, but wasn't sure. The only problems I could think of would be that the magazine spring retainer would need to be watched when the cap was removed because it would be able to pop out, and that the retainer would have a tendency to rotate along with the cap as it was screwed on and off.

So, does eliminating those indentations preclude the reverting of the magazine back to its standard state?


Badger Arms
September 22, 2000, 06:42 PM
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by BAB:
So, does eliminating those indentations preclude the reverting of the magazine back to its standard state?[/quote]

No... The only difference is the plug will rotate now and the nut may come loose. On previous guns without the dimples, a detent and spring were used on the face of the magazine lug to prevent the cap from rotating. What you'll want to do is make sure that the cap is secured somehow from turning. Tightening it well should help in this.

God made us in his own image.
Thomas Jefferson made us free.
John Browning made us equal.

Without Browning, we might not know about the other two...

September 23, 2000, 12:49 AM
Thanks badgerarms!