The explosions are easy to do in a script, but why the bullets? On a normal bullet, you have to hit the primer with fair degree of force for a clean firing. I would think that heating a bullet would weaken its casing to the point where, when the gunpowder went off, there'd just be a bit of a pop and the casing would be blown to bits. Well, OK, the bullet would be propelled a bit, but it wouldn't be going too fast.
For the explosions, here's a piece of a script:
;Script starts here
#Start
_boom = getpos ammotruck
_bx = _boom select 0
_by = _boom select 1
_bz = _boom select 2
#Update
_power = "heat120"
_tempobj = _power camcreate [_bx,_by,_bz]
~.01
_tempobj = objnull
#RandomWait
_waitperiod = random 25
~_waitperiod
goto "Update"
#Exit
This creates 120mm HEAT shells repeatedly on the target at random intervals. Modify this if you want to. It requires a target called "ammotruck". The rounds have a fairly large radius, so it could be an unpleasant surprise.