View Full Version : Benelli 4 round mag extension will not work - help.

August 8, 2002, 12:20 PM
I have an M1S90 Field. I bought the factory 4 round magazine extension kit #80155. After installing it, the magazine holds a total of 4 shells! With this extension it should hold 7.

The first thing that strikes me is that the spring included in the kit is LONG. Really long. I am sure the spring is binding in the tube making the additional shells impossible to load.

The factory does not have a clue why this does not work. Does anyone have any tips?

Al Thompson
August 8, 2002, 01:59 PM
Dimples? Have you looked through or in the magazine tube to see if there's something blocking it?

May be that the folllower can't jump the joint where the extension and magazine tube are joined. IIRC, that point would correspond to where about four rounds would stop.


August 8, 2002, 04:01 PM
When I bought my pre-ban Super90s, they came with the extended mag already installed. One thing that the owner had to do with these hi-cap Super90s was to remove the magazine plug from the magazine.

Is there a plug in your extended mag? It should be no more than an aluminum rod about 3/16" in diameter with a washer-like thing at the end.

August 8, 2002, 04:24 PM
Thanks to all. The plug is not in the gun. I suspect the spring is about 50% longer than it needs to be. Very strange.

August 8, 2002, 06:33 PM
The two shot extension for my Nova had a super long spring as well. I had to cut mine down to get the proper number of shells to fit.

August 8, 2002, 07:15 PM
My M1S90 also came from the factory with a 7 round mag ... the spring was very stiff at first but it still held 7 rounds. Very strange.


Al Thompson
August 8, 2002, 08:38 PM
Dave, have you tried removing the magazine spring and loading 7 shells in the gun? Just trying to eliminate the possibilities..

August 9, 2002, 09:49 AM
Thanks again to all. I tried it assembling and disasembling the mag tube four times last night. On the last try - ALL seven rounds fit. Wierd. The spring seemed noticeably less stiff. Maybe it was binding up inside. It is not doing it now though.


Sea Bass
August 10, 2002, 03:53 PM
Hi Dave,

I too at one time had the extended tube on my Benelli. I had the same problems. The spring was indeed binding up inside the tube. I eventually sold it and stayed with the short mag tube.

August 26, 2002, 07:59 PM
...but I recently put the two shot extension (which is a 3 shot if you use 2 3/4" shells) on my Nova. I noticed that there was a little "button" like end cap at the end of the extension that is similar to the Choate extensions.
I usually push on this a bit to relieve some of the tension and possible binding in the spring. I figure that the binding may occur during the screwing on the of mag extension. On first try, my magazine capacity didn't increase, but by lubing the spring and holding the button down while re-installing the extension, I ended up with the full capacity.

I can't remember if the barrel clamp came with a nut for the screw, because my clamp happened to move forward while I was doing some double-tap dry-firing. Any help?

September 27, 2002, 06:55 PM
I had a little trouble installing my extention on my Nova.

The spring appears really long- but only because it hasn't been compressed and taken a set. When I compared the stock spring with the factory extended mag spring I noticed that the stock spring's spirals were noticeable closer. When I first assembled it, I could only load 4 rounds. I left the rounds in the tube and carefully unscrewed the tube, then barrel retaining nut. As I unscrewed, I heard the spring jump in the extention. After that, I tightened it back down and could load 7 2 3/4" shells.

I think that the spring might be pinched when you first install it, due to the uncompressed length. I suspect that a coil of the spring gets caught in the threads between the end of the mag tube and the barrel retaining nut. Upon examination, I notice a small ledge in the middle of the nut.

Hope this helps.

January 7, 2005, 05:43 AM
+1 for the magazine spring pinching.

I recently installed a +4 on my Benelli Super 90 and it would only load (3) rounds. I unscrewed the mag. ext. a little and banged the butt of the shotgun on the ground a little, then tightened it back up and it would load the full amount. It seems, as previously posted, that the threads caught a coil of the spring and would not allow it to compress further.