RAW, Jury Rigged applies to each activation. I'm thinking this might be a decent house rule though. It wouldn't absolutely gimp the build, and would bring its effect in line with the other benefits of Jury Rigged, like Damage +1 and the reduced cost of activation of other qualities, which usually can only be activated once (contrary to Autofire, which is endlessly repeatable). I might as well apply it to the critical injury rating reduction as well, so for example, it would only affect the initial "triggering" of the crit, not all the other activations that add +10 on the Critical Injury table.
What do others think about this? Is this too much of a nerf bat?