1. Pick ammunition
2. Consider features
3. Fudge factors
4. Finalize the numbers
The first thing to do, when designing a gun, is to choose the ammunition the gun uses. You don’t necessarily have to pick the exact caliber at first, just the general type is often enough to get you started. This will give you an idea of the base range and the damage of your gun.
Next consider the features your gun has. Is it a Rifle, Handgun or Heavy Weapon? Does it incorporate special features such as built in smartlinking, etc.? Is it generally well made, or did they cut corners in the design?
Based on your features you should have a rough idea of the price-range your gun should fall in.
How good is the design? Is it more than the sum or its parts? Less? Feel free to fudge the WA up or down by a point, or even two if you are feeling extreme. Finalize the WA, range increment, reliability and ROF of the gun. Choose the cost. Note that the only way to change the damage is normally by changing the ammo used: you can’t really fudge it or the whole system gets fucked.
Finalize the numberes
Write down the finished form of your gun.