This is a discussion on drilling out tabs for mag extension on an 870 within the Defensive Rifles & Shotgun Discussion forums, part of the Related Topics category; The instructions say to use a 3/16th" bit to drill the tabs out, I'm now up to a 1/4" bit, and the replacement magazine follower ...
The instructions say to use a 3/16th" bit to drill the tabs out, I'm now up to a 1/4" bit, and the replacement magazine follower still can't fit past where the tabs used to be. I'm afraid the tube itself has warped slightly from round??
I'm having a hell of a time with this...I suppose I could just keep going to a bigger drill bit, but this is starting to get ridiculous.
Anybody done this?
Drilling from the outside will leave a bur on the inside. You'll probably need to ream out the inside of the magazine tube to remove the burs that keep the follower from fitting inside. A Dremel tool would do the trick I would imagine. If you don't have a Dremel or such, you could always do a makeshift hone out of the drill bit you are using and wrap some fine grit sandpaper around it and tape it at the base of the bit. Whatever size drill bit you use, I'm sure it will have to be a larger diameter than the dimple you are trying to remove. You might want to center punch the dimple in order to center the bit better. I have never dealt with this issue, but I know what you are talking about. Good luck.
If you use an X-acto knife with a #11 X-acto knife blade you can angle it and slice away the burr that is on the inside of the hole. The harder steel of the blade will cut the softer steel of the tube.
I took a 1/2 drive socket that just fit in the tube, drove in down, and that forced the dimples back out, and did not put holes in my tube. works fine. I think I used a 7/8" socket......
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Burrs are not the problem; I reamed it out pretty good w/ a slightly smaller bit, ran my finger on the inside of it until it felt smooth, and even test fit a shell...which is just slightly smaller than the follower.
It sort of works, but sometimes the follower gets stuck if I load more than the standard 4 shells, and the follower that came w/ the choate extension tube is ridiculous.
I think I just need to keep at it; doesn't sound like I can do any serious damage.
Chamfer the throat of the mag tube, ie, use some wet-dry 400-600 grit and bevel the opening. The hang-up with partial loading as you describe is usually caused by the throat.
I used a dremel and smoothed/ground off the tabs . Finished with a sanding drum it worked well.
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More advice? Get one of those hi-vis followers for your shotgun. Got mine on EBay. Won't bind or let the spring get past. Good investment for a few bucks IMO.
So I got a nice little aluminum follower, which works great, however, I found that it sometimes gets caught up on the threads of the mag extension...
Thinking maybe I can get some teflon tape to fill in the gaps?
It should feel like a funnel. The only way the extension threads are causing a problem is if there are some MAJOR burrs, which should be readily visible.Chamfer the throat of the mag tube, ie, use some wet-dry 400-600 grit and bevel the opening. The hang-up with partial loading as you describe is usually caused by the throat.