The M-Rod Double

Soon to be available through Stalwart Arms.

The M-Rod Double kit is an easy-to-install second air tube for your Generation 1 or Generation 2 Benjamin Marauder rifle. The kit weighs only eleven ounces but increases the air capacity by 60%. That extra air can give you 60% more shots, or it can help restore the shot count you might have sacrificed for power modifications. Prior experience with assembly and dis-assembly of the Marauder rifle will make installation of the kit go more smoothly. Familiarize yourself with the installation instructions before attempting installation.

The kit is $215 plus $15 S&H and includes:

  • 2024T3 high strength aluminum alloy air tube, powder coated black
  • 1” diameter x .095” wall
  • 18.04” long (132 ccs) for Gen 1 Marauders
  • 18.87” long (139 ccs) for Gen 2 Marauders
  • Threaded 6061T6 aluminum plugs for both ends of the tube
  • Stainless steel air transfer fitting
  • Aluminum barrel band, powder coated black, with single Picatinny rail on the bottom
  • A complete set of spare o-rings, with o-ring lube

Pictured above is the complete kit, showing all the components. The kits work for all three calibers of rifle. The only difference between the Gen 1 and Gen 2 kits is the length of the air tube. The design of this kit is very similar to the P-Rod Double Kit, with its hundreds of successful field installations.

The new 1” diameter tube is connected to the original 1-1/4” diameter main tube by the air transfer fitting that installs into the gauge port inside the main tube. The air pressure gauge is relocated to the front of the new tube. The new powder coated barrel band clamps the two air tubes firmly together, but allows the barrel and shroud to float the same as in the factory configuration. The barrel band has a Picatinny rail on the bottom which can be used for installing a bi-pod, light, or other accessory.

The M-Rod Double kit installed on a Gen 2 rifle, and installed in a new stock from The factory Gen 1 stock can be inlet to accept the new 1” diameter tube. Because the inletting is 1” deep, it will protrude through the bottom of the front end of the stock. For the Gen 2 Marauders, neither the synthetic nor the wooden stock has thickness needed in the bottom to allow for inletting for the 1” tube. A new stock will be needed.

Comparison specifications of the Gen 1 and Gen 2 Marauder rifles with and without the M-Rod Double Kit. The kit weighs 11 ounces and boosts the air capacity by 60% to 352 ccs for the Gen 1 and 371 ccs for the Gen 2. Although both kits weigh only 11 ounces, the weight increase of the finished gun will vary from approximately 3% to 17% depending on the type of stocks used.

Here are some of the dimensions that differentiate the Gen 1 and Gen 2 Benjamin Marauder Rifles. One of the easiest ways to tell the difference is by looking at the back end of the receiver. On the Gen 1, the back of the receiver is flush with the back end of the main tube. On the Gen 2, the receiver is approximately 5/16” forward of the end of the main tube. The correct kit must be chosen so that the front of the new tube lines up properly with the barrel band.