Shotgun Forum banner

870 magazine cap. What are the thread dimensions?

8K views 5 replies 4 participants last post by  Virginian 
#1 ·
I have invented a gadget that will replace the magazine cap on a Remington 870. I can't seem to find any standardized nut or collar that is threaded to fit it. Is this some proprietary Remington design or is there some standardized off the shelf nut or collar that will allow me to adapt my invention? It has to be possible as there are a number of after market magazine extentions that screw on.

Thanks, ES
 
#2 ·
It is an ACME thread. I don't know if it's "standard" or not, and all my stuff is at work. Measure it, figure the threads per inch and make sure it's single lead (I think it is) and go to McMaster Carr and see if they have a nut or a bolt that matches what you got.
Everyone says "metrics" are so great; easier. Except they have 3 different threads on most sizes of fasteners, not just fine and coarse.
 
#3 ·
Boy howdy on the Metric stuff!

It isn't rocket science to figure out the thread. A screw pitch gauge, and a mic or dial calipers will pretty much do the job. I don't recall for sure, been quite a while since I took my 870 end cap off, it may not be Acme, they may be square cut threads. I believe it is a single pitch though. Get out your tool grinder and a bit of MoMax and grind yourself up a threading tool and have at it. I suppose you could buy a ready ground one from MSC or JTS or the like.

Assuming it is a standard of some kind or other is probably naive.

I doubt it!

BP
 
#4 ·
Virginian said:
It is an ACME thread. I don't know if it's "standard" or not, and all my stuff is at work. Measure it, figure the threads per inch and make sure it's single lead (I think it is) and go to McMaster Carr and see if they have a nut or a bolt that matches what you got.
Everyone says "metrics" are so great; easier. Except they have 3 different threads on most sizes of fasteners, not just fine and coarse.
it is not an ACME thread. It is a 1.0 inch 12 pitch single lead square thread. I recut mine after I shortened my mag tube.
 
#5 ·
I can not edit my post in this forum, so I have to make another post.

Here are a few pics of my 870 mag tube after I cut it down and rethreaded it. I also machined the mag cap.
a standard cap still fits, I just wanted something differant




 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top