Echo1 M240 Bravo PolarStar Fusion Engine Conversion

Here’s another monster gun that is just begging for a PolarStar Fusion Engine. The Echo1 M240B machine gun is a big (very big) airsoft gun that fills the role for a support gunner extremely well. The gun is almost 50 inches long, and weighs in at 22 lbs loaded. It has a 4000 round box mag so you can have plenty of ammo for cover fire. I’m sure it’s a decent gun with the stock AEG gearbox, but put a Fusion Engine in this beast and you can empty that box mag in one go without worry of breaking anything (just have a nice big air tank!).

The Echo1 M240B has a unique gearbox that is held in place with 3 screws. Two screws in the back attach to the trigger switch bracket, and one screw in the front attaches to the hopup well.The hopup well is then attached to the body by two screws. The trick for mounting a V2 Fusion Engine into the M240B is to reuse the mounting points of the stock gearbox. This can be done by fixing the hopup well to the front of the Fusion Engine cylinder by making a small bracket, and then making a longer bracket on the back to attach the switch bracket, which can be easily removed from the stock gearbox.

The nozzle on the M240B is a little shorter than the stock M4 nozzle, so a little milling and profiling is needed to match the standard M240B.

With the Fusion Engine in place, there is plenty of room in the body of the M240B. The standard configuration of the gun is that it fires full-auto only. With the extra space, a fire select switch could be added to allow the gun to fire semi-auto if desired.

The same trigger relay modification that I have done with the Stoner 63 and the Mk46 sends added to power the box mag when the trigger is pulled. This box mag does not use a hi-cap type of feeding mechanism but rather a paintball hopper-like feeding mechanism, which I think works very well. The box mag only activates while the trigger is pressed, and it seems to be able to keep up with the BB feeding quite well.

Since this modification does not use the lower half of the Fusion Engine, I used a my custom trigger circuit board so it will take up minimal space in the body. The trigger mechanism occupies the entire grip space, so it was not practical to have the air line exit from the grip, so the air line was routed to exit out the bottom of the stock. To make removing the stock easier, I added a QD to the macroline.

This gun is heavy. I had to do all the test firing from the floor of my workshop as I couldn’t shoulder this gun (not for very long anyway). Since box mags generally feed slower than mid or high-caps, the nozzle dwell should be set to 30 to give time for the BBs to seat in the hopup properly. But it fires very cleanly and smoothly once configured correctly. It’s amazing how fast this gun makes a bag full of BBs disappear!

Lee Nugent sent out this Echo1 M240B to be converted. He said to “use it as my canvas.” This machine is already a work of art, but now it has the brawn to back it up the beauty!

Happy Airsofting,

– captainbingo