This is the solution i thought and posted in a italian forum where Benkalas wrote at first, it is based on the 3 "steps" wrote on the SRD:
-Will ST for magical weapon (nothing new, just SRD)
-Will ST (or Fortitude; DC= the same as before +3/+5, i'm not used in calculating those kind of things) to make people don't throw the weapon away or to let them pick it up during the "Searing" step
-25% chance to andconsider the weapon as "Broken" for Searing time and waste all ammo left inside (throw dice once at the beginning of Searing step)
-Loading time increased by one step from "Hot" to "Hot" step
-Halved range during "Hot" to "Hot" steps (this is because it's hard to aim with a red hot iron in hand and makes simple to calculate penalities)
-*this may be too much* 10% chance accidental shot if the firearm is dropped; calculate the direction by a d20 or d10, the gun uses its own magical bonus (+0 to +5)$ and hits the first thing on ammo's path
Sorry for my bad english, i hope you can understand :P