the only surplus ammo i use is the 5.56mm for the light machine. it is stronger then the standard and can get lots of it. good for killing nastys with low or no DT. not the best but can get lots of it.
i like the .50mg boom. not as good as a missle launcher. but still satisfying when taking 3 or more lesser nastys with one shot,
for the riot shoot gun, magnum. though i use the store bought ones. it is easy to create as much magnum as i need.
so what ammo do you use?