Remington 870 Magazine Thread Specs

[a5werkes]

I want to shorten a 870 magazine tube and re-thread the end. Anyone know the correct type and pitch of the the threads? Thanks.

 

[Kp321]

Question. What are you going to do about the magazine ring on the barrel? Unless you move it back a corresponding amount, no use shortening the mag tube.
I am away from home right now so can’t measure anything but I can tell you the threads are not anything standard. They are either square or stub Acme and much shallower than normal. No dies available which means lathe threading which entails removing the mag tube from the receiver. While it is out of the receiver, just whack some off the back end and leave the threaded end alone.

 

[BigBlue 94]

It is a "stub" thread. Not sure if it can be classified as ACME or square or what. It is approximately 1"× 10TPI, judging from memory on my 20ga. Threads look like acme shape, with squared roots and crests.

 

[beag_nut]

I second what KP321 said. Even if you know what the thread specs are, how will you use a die without removing the tube first? The dies have relatively large outside dimensions. Probably won't fit with the barrel in the way.

 

[BigBlue 94]

I second what KP321 said. Even if you know what the thread specs are, how will you use a die without removing the tube first? The dies have relatively large outside dimensions. Probably won't fit with the barrel in the way.

Remove barrel and its quite easy.

The big issue is shortening the mag tube very much will run into issues with the forearm tube liner.

 

[nulook45]

Keep in mind the tube is induction welded into the reciever if you break it lose your screwed it has to be returned to the factory for repairs .