870 Magazine Tube thread?

[Synchronizor]

I had a friend get me a nice front sling plate for Christmas (rather, he got me a gift card to get it myself, he doesn't know shotguns). I like the part, but the plate is just thick enough that even with the extension tube screwed all the way down, a gap remains inside the coupling nut that causes shells to hang up.

The entire problem would be solved if my extension tubes had 1/8 of an inch of extra thread on them, but I've been unable to determine the exact thread type Remington uses on the 870's magazines. Hopefully, it won't be something too rare or proprietary, since they seem to stick with standard threads elsewhere in the gun. There are also plenty of independent parties that seem to have no issues cutting down and re-threading the magazine tubes when building shortys.

Remington 870 Extensions_thread.JPG (22.46 KiB) Viewed 6664 times

Does anyone here know what that thread is, and/or where I might find a die to match it?

[Kentactic]

Are you screwing the Locking nut all the way as tight as it goes before you screw the extension on? You said a couple different extensions have the same problem? is this a gun issue?

[Synchronizor]

Are you screwing the Locking nut all the way as tight as it goes before you screw the extension on?

Yes, I tighten the coupling nut all the way down, then insert the spring and screw on the extension tube.

You said a couple different extensions have the same problem? is this a gun issue?

I use Remington extensions, which have the same thread dimensions and use the same coupling nut. The issue is that the tubes won't screw quite far enough into the coupling nut to fully compensate for the the sling plate spacing the nut away from the barrel's mounting ring.

I can tell this is the case because with the sling plate installed, the end of the installed extension tube is farther forward than without it. This wouldn't be the case if the magazine & extension tubes were properly butted against each other, either with or without a sling plate under the coupling nut.

[Kentactic]

I see, now if i understand you correctly theres a sling plate that is between the nut and the barrel ring? If so that would make the extension have to thread deeper into the Coupling nut, requiring more threads on the extension. Does the extension seat properly without the sling plate? Im guessing your going to say yes and now im up to speed lol. So your sling plates screwing you over basically and your trying to make it work right?


So why not get one of these and call it good?

http://www.mesatactical.com/images/96.jpg

[Synchronizor]

So why not get one of these and call it good?

A) I wanted a sling plate, not another barrel clamp

B) that product is $55 just for the bare clamp. Then, you have to buy the rail or sling loop separately.

C) While I have no issues with Mesa Tactical's products (aside from the prices), their marketing bugs me. The picture you referenced tries to make the product more "tacticool" by showing it on a ported barrel (which does nothing but ruin a good barrel and annoy whoever's next to you at the range) with a second sling plate tossed in for flair or something. Even their logo sends a message that's pointless at best, and damaging to the image of the shooting community at worst.


Now, point "C" is just an opinion, and isn't intended to intimate anything negative about the products or the people who use them. That whole "tactical-ninja/terrorist image and the people who try to capitalize on it are just personal turn-offs.

[Kentactic]

Yeah their logo is about as retarded as a football bat, i agree.

What if you just chopped the required amount off of your locking nutt? Im not looking at a nutt right now so it might cause an issue but thats one idea to look at. Seems easier then threading the extension more.

[Synchronizor]

What if you just chopped the required amount off of your locking nutt? Im not looking at a nutt right now so it might cause an issue but thats one idea to look at.

I've thought of that. It's plan B.

But I'd prefer to know what the thread is and have the tools to cut it; both for this project, and for designing and building custom extensions or other accessories in the future.