So, I'd still like to do this:
Gravite: Gravite is a metallic substance with unusual properties. However, until recently, it was no more than a curio; Gravite objects weigh different amounts depending on their orientation, which has for centuries baffled scientists. However, recent breakthroughs in theoretical physics indicated that Gravite might be more than just a curio- it might be one of the most important substances on the planet. An eccentric physicist by the name of Ernesto Pondus recently penned an article describing a theory of gravity that overturns the conventional model- something about family members? Professor Pondus also indicated that, properly treated, Gravite could be used to warp the effects of gravity significantly. By subjecting molten Gravite to a strong, mono-directional source of radiation, the molecules can be aligned, turning the random effects on gravity into a consistent, controllable phenomenon. By maintaining the radiation until the Gravite cools and solidifies, the effect can be 'locked', creating 'Alligned Gravite'.
We've done this, creating bars of solid Gravite that float upwards, in defiance of conventional physics. With the appropriate equipment and forging techniques, we can create Gravite objects that project almost arbitrary gravitational fields. Even more powerful effects can be achieved by keeping the Gravite (which has a relatively low melting point) in a molten state, allowing for the strength and direction of the gravitational effect to be modulated by changing the strength and direction of the radiation being directed through it.
For the MG, a problem occurs: the Gavrilium cooling rod doesn't have any outlet for its energy, so how do we cool it down? Might I suggest the following alternative:
GGG-12: Sometimes a throwback isn't a bad thing. The Gavrilium Gatling Gun is an example of this.
Unlike a machine gun, the action of firing does not itself cause the weapon to cycle. Instead, a very small Gavrilium Engine (with short, stubby rods) is used to rotate the three firing chambers, loading and firing each through the single barrel in turn. It does so at truly breathtaking speeds, firing incredibly powerful 7.7G rounds (7.7mm bullets with Gavpowder propellant) from belts, resulting in long-range devastation unmatched by contemporary weapons.
Naturally, the extraorinarily high rate of fire and powerful cartridges results in a lot of heat being generated, which would ordinarily require considerable cooling- making for a very heavy weapon. But this is the beauty of the GGG; heatsinks attached to the engine take care of the cooling problem, adding only a little weight, resulting in a weapon that, whilst not lightweight, can still be transported fairly easily, especially since it can easily be disassembled into three parts (the engine, the firing section, and the barrel).
Four soldiers (one carrying each part, and the fourth ammunition) will crew the weapon. It is also suitable for installation on vehicles of all sorts. The rate of fire can be adjusted as circumstances dictate, by turning a dial.
Or something along those lines, please feel free to suggest modifications, or copy this and change it to fit your whims. But barring changes, I'd like to do Gravite as our 'standard' design, and use the RC on the GGG-12.