Best Benelli M4 Mod – Installing a Benelli M4 Magazine Extension

The best Benelli M4 Mod you can make is the addition of an M4 magazine extension. If you could only choose one of all the Benelli M4 accessories available, the M4 extended magazine makes the most sense. The magazine extensions for the Benelli M4 Super 90 come in several styles. The full length magazine tube in steel, the full length tube  in titanium, the 2 round add on magazine extension in steel, and the 2 round add on for the Benelli M4 in titanium.

NOTE: The Benelli M4 capacity numbers we are spouting here are for 2 3/4 inch shells. The M4 can use 3 inch shells but that decreases capacity, and 2 3/4″ shells are more than adequate for the close range use of a Benelli M4 tactical shotgun or any other for that matter.

The titanium magazine extension for the Benelli M4 is about half the weight, saving about 5 Ozs on the steel tube extension. The cost of a titanium tube extension is twice to three times the price of the same item fabricated in steel. But there is that 5 Ozs of weight saving.

Prices range from about $40 at the low end to over $200.00 at the high end. I paid $75.00 for mine direct from the manufacturer and after researching further, I found the same part on MidwayUsa for $5 less. Of course I had already placed the order. So much for spending money while you are excited about your new shotgun and can’t wait to add a magazine extension.

Benelli M4 Mag Extension Full Length

Benelli M4 with Full Length Mag Extension

NOTE: The Benelli M1014 military version of the M4 has a full length magazine tube which allows 7 shells in the magazine and one in the chamber. An additional round can be floated on top of the carrier as specified on page 22 of the Marine M1014 manual. Floating a round increases the capacity to 9 rounds. You can float a round without the extended mag and still end up with a capacity of seven shells in the shotgun.

Some sources for magazine extensions for the Benelli M4 Tactical Shotgun include:

Original Benelli add on two piece extension $159.00 – $250.00. Find on Gunbroker.com

Dave’s Metal Works – Full length one piece tubes $60.00 and add on two piece tubes $70.00.

TacStar – Add on two piece tubes about $60.00

Freedom Fighter Tactical – Titanium full length mag extension tube and Add on two piece titanium extension tube about $200.00

CarrierComp – Titanium quality full length tube extensions $189.00 when on sale.

Gunbroker.com – Selection of manufacturers and price ranges.

Brownells – Selection of magazine extensions

MidwayUsa – Selection of magazine extensions including Dave’s Metal Works

I purchased the Dave’s Metal Works two piece extension for my Benelli M4 Tactical Shotgun. I just could not bring myself to apply heat to the receiver to loosen the LocTite on the factory magazine tube. Even though I had experience with the process while working on EOD robots in Iraq, I had just spent $1600.00 for a very nice Benelli M4, so maybe you can understand my hesitation.

Benelli M4 Mag Extension Daves Metal Works

My M4 with Dave's Metal Works Add On Extension

That’s why I opted for the Dave’s Metal Works add on two piece extension. I had purchased an Easy Loader for my Remington 1100 which is a Dave’s Metal Works product, so I knew the quality of his products is top notch. My magazine extension screwed right on, looks great, and works flawlessly. I am very happy with it for an investment of $75.00. Get the same part through MidwayUSA for $69.95.

Special NOTE: I purposely used the Dave’s Metal Works two piece add on extension because I did not want to apply heat to my shotgun. The two piece extension works great! The installation instructions below are just to show the procedure that I decided NOT to use on my shotgun. Many persons have installed the one piece tubes without incident. I haven’t heard of anyone talking about overheating their shotgun. Of course, if they ruined a $1600.00 Benelli M4 they probably wouldn’t want to talk about it. If you decide to heat your M4 and cook it, then that is on you. I am happy with my two piece add on extension.

This is not intended to be aprocedure about How to install a Benelli M4 Mag extension. This just relates what others have reported on the Internet about installing a full length magazine tube on a Benelli M4 tactical shotgun.

Installation of Benelli M4 Full Length Magazine Tube

The Benelli factory installed tube is set in LocTite. There are three grades of LocTite, blue is the weakest, red is next, and green is the strongest. LocTite can be loosened by applying heat of about 300F to 500F depending on the type of LocTite.

  • Make sure the weapon is safe and not loaded. No rounds in the magazine, no rounds in the chamber.
  • Get a heat gun, pot holders, or something to safely twist the magazine tube after it gets hot, snap ring pliers, and eye protection.
  • Wear eye protection.
  • Field strip so you can see the factory magazine tube threaded into the receiver.
  • Wear eye protection Then remove the snap plug that holds the magazine spring in place. There are two to remove, one on top of the other.
  • The spring will shoot out with great force if you are not careful.
  • Remove the follower
  • Use a heat gun to apply heat to the outside of the receiver.
  • Don’t use open flame, it may discolor the finish.
  • Don’t apply heat the magazine tube, just heat the receiver.
  • Using oven mitts or pot holder twist the factory tube out of the receiver. The temp will be about 250F to 300F at this point.
  • Don’t forget to transfer the hand guard rear brace, it has to be in place on the new tube BEFORE threading it into the receiver.
  • Install the magazine tube extension while the receiver is still hot and the LocTite is soft.
  • Hand tighten the new tube, don’t use any tools.
  • Let it cool.
  • Reassemble your M4.
  • Take it to the range to test.

NOTE: If you decide to use LocTite then clean the threads and use Blue LocTite. I would not use the LocTite. The heated receiver will shrink down on the new tube and will be plenty tight.

NOTE: Check the laws in your state to make sure that increasing magazine capacity is legal.

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