I just brought home a Benelli M2 tactical.  I bought a Nordic Components extension tube that was supposed to hold +3.  My Benelli from the factory has a 5 round magazine so by putting on the +3 Nordic tube, I should be able to put 8 rounds in the magazine.  After making several cuts to the 40" magazine spring, I was never able to get more than 2 additional rounds in the gun.  I cut the spring down gradually each time - eventually cutting off 5 pieces.  The spring is so short/weak now that it won't even feed the last round onto the shell carrier and I still can't load 8 rounds in the magazine.  Anyone ever run into this problem?

uh, just to be sure, how exactly long is this +3 extension?

here is a pic of my M2 tactical with a +2 extension (8 total, 7 in the mag +1).

What did the factory cap on the tube look like?  Sort of like a +1 extension?  

The +3 Nordic extension adds 3 rounds to a standard M2, which only holds 3 in the tube.  The factory Benelli Tactical holds 4 in the tube due to the factory +1 extension.  To hold a total of  8 in the tube, you need a Benelli +5.  

See the picture of how to measure on Nordic's site:

http://shop.nordiccomp.com/NC-Shotgun-Extension-Tubes-for-12ga-12GA-EXT.htm

RedZ71, are you sure your extension isn't a +4?

Benelli M2 holds 3.  Add a +3 extension and it should hold 6.

A M2 that originally held 5 in the magazine would have already had a +2 extension.

The Benelli website lists the M2 Tactical capacity as 5+1.  "Common specifications: M2 and M3 Magazine Capacity: 5+1 Chokes: IC, M, F Crio® Chokes (Fixed cyl. on M3) Length of Pull: 14-3/8" Drop at Heel: 2" Drop at Comb: 1-3/8" Benelli M2 Tactical.

Apparently Benelli sends them from the factory with a +2 extension to hold the advertised 5+1 capacity.

(Oddly enough, nowhere in the factory manual does it list the magazine capacity.)

The "+3" tube I bought is 8.5" long.  It is about 2/3" shorter than the 18.5" barrel when the extension is installed, and I don't want a tube that extends past the barrel.

The magazine end cap and tube that came with my shotgun is 4.5" long.

I guess I'll just have a shotgun that "only" holds seven in the magazine!

did you install the shorter follower? my m2 had 2 followers in the box, I always use the longer one to make it legal to hunt with

Mine only had the follower that was already in the magazine.

The M2 mag tube itself holds 3 rounds with a flush mag cap (no extension), giving the capacity of the gun 3+1

The Tactical model of the M2 has a "+2" magazine extension from the factory, giving the capacity of the gun 5+1

If you took off the "+2" extension and added a "+3" extension, your total capacity should be 6+1





ETA: If you're getting 7 rounds in the mag, I'm betting they're star-crimped 2&3/4" shells, and probably a tiny bit on the short side.  If you put roll-crimped 2.75" or 3" shells in, you'd only be able to fit six.

Thanks for the answer.  I am using 2 3/4" star crimped shells.  I'll have to remember that if I switch to different loads in the future.