Grizzly mag modification

Butcherbill

Butcherbill

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So I grabbed a couple extra grizzly mags for my 12.5", while I was tweaking the feed lips and de burring/polishing some spots to make them feed smoothly I had a thought.

The follower itself is fairly tall, I'm able to trim off some of the bottom by the looks of it. I can load 5.5 12g shells as it stands from the factory, is there anything stopping me from trimming the follower to get a full 6 shells in the mag? 6+1 in a 12.5" shotgun would be nice.

It's pump action so theoretically I should be good to trim, no? Or is there a semi this mag will fit in or was designed to fit in? I haven't seen a semi auto mag fed grizzly/870. Or is there any law saying otherwise. Just mulling things over at the moment and thought I'd run it by some other people. Extra capacity in a small package is always fun.
 
0zfE9p6.jpg


It takes a bit of work but it will hold 6. you can see in the pic that you need to drill out the stops on the mag as well.
Also the springs need to be shortened.
This is a project I still need to finish but I have finished and tested 2 mags.
 
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There's a few vendors who are making magazine extensions for the Turkish shotgun mags.

I'll bet you could make one fit a Chinese magazine pretty easily.

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ht tp://www.taccom3g.com/taccom--11-round-extension-.html
 
They are totally different.
Click to expand...

The body size is totally different?

The extension just bolts onto the outside of the existing magazine body.
It can't be that hard to make it fit.
 
Dennis001 said:
Any step by step guide how to make them run reliably, noobs here, thanks and have a good day
Click to expand...

This is what I did to make my 12.5" mag fed feed reliably.

Thoroughly clean it after you get it. Debur and polish any internals, chamber, action bar, feed ramp, mag lips and front inner edge at the top of the mag. That made things smooth as butter when cycling the action, I found that the aftermarket metal mags have a longer magazine spring than the stock metal mag. I had to tweak the mag lips in a bit to match the stock factory metal mag. The factory mag has always fed fine for me with 2 3/4" shells.

I trimmed a coil or two and matched the springs in length, feeds great now. Springs were too stiff and shells would jam on the second round. They like 2 3/4" shells more than 3", have a feeling that more filing and polishing of the inner edge of the magazine will allow 3" to feed.

I like to fiddle and tweak so it's been fun, if you don't like to #### with things buy a tube fed grizzly. My mag fed is getting to the point where I trust it to load 2 3/4" loads 100% of the time, confident I can get it to feed 3" as well.
 
the problem with the mags is that they do not hold the 2 3/4 shells properly. in matches they always jam. i found that the round at the top of the mag moves too far forward during recoil. when the action is cycled to the rear, the spent shell ejects then the shell at the top of the mag pops up into the chamber area and jams when the bolt moves forward. that shell never gets stripped from the mag, but the bolt does strip a second shell. double feed.
 
Thanks for the reply


Butcherbill said:
This is what I did to make my 12.5" mag fed feed reliably.

Thoroughly clean it after you get it. Debur and polish any internals, chamber, action bar, feed ramp, mag lips and front inner edge at the top of the mag. That made things smooth as butter when cycling the action, I found that the aftermarket metal mags have a longer magazine spring than the stock metal mag. I had to tweak the mag lips in a bit to match the stock factory metal mag. The factory mag has always fed fine for me with 2 3/4" shells.

I trimmed a coil or two and matched the springs in length, feeds great now. Springs were too stiff and shells would jam on the second round. They like 2 3/4" shells more than 3", have a feeling that more filing and polishing of the inner edge of the magazine will allow 3" to feed.

I like to fiddle and tweak so it's been fun, if you don't like to #### with things buy a tube fed grizzly. My mag fed is getting to the point where I trust it to load 2 3/4" loads 100% of the time, confident I can get it to feed 3" as well.
Click to expand...
 
P0WERWAGON said:
the problem with the mags is that they do not hold the 2 3/4 shells properly. in matches they always jam. i found that the round at the top of the mag moves too far forward during recoil. when the action is cycled to the rear, the spent shell ejects then the shell at the top of the mag pops up into the chamber area and jams when the bolt moves forward. that shell never gets stripped from the mag, but the bolt does strip a second shell. double feed.
Click to expand...

I found with my metal mags that bending the lips in a hair helped to hold the shells in the proper place, before I bent them in they would allow the shell to slide forward or upward when initially seating the mag. Doesn't seem to be a problem anymore with 2 3/4" shells.
 
The best thing i did to mine was to make a feed ramp between 4:30 and 7:30 on the barrel this helps a lot with feeding, more so than the dimpled mag fix alone.
20160702_172011.jpg

left is the modified barrel right is a new barrel.
Done with a sanding drum on a dremel. Match it up to the feed ramp inside the receiver like this.
20160702_173358.jpg

This is the unmodified one to show the difference.
20160702_173504.jpg


If you're having problems with hulls not fully ejecting enlarge the ejection port. This was done in a mill don't try to do this by hand.
20160702_171847.jpg

Top is a squared up enlarged port.
 
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