Yay activity!
Gisk is right about the threshold, and Pathfinder about the momentum. I'll have to add a bit to that. Scarifar brings up a good point, so I'll take Lenny a few notches down from being totally bulletproof. Once the threshold is reached in terms of absorption, I imagine they'd be sorta like rubber bullets. Might not break his skin, but will definitely leave a nasty mark and take the wind out of him in the right spots.

Edit: Didn't mean to leave Avanhelsing outta the discussion. The similarities are coincidental, but I can see what you mean. I'll expand more on the concussive nature of whatever Lenny fires (Bolts/Missles/Waves/Blasts/What Have You). Otherwise, I don't think the electricity motifs will clash very much. Lenny is more of an energy sponge than Kyle, who sees more along the lines of an electric elemental. They'd probably work in tandem in combat, which would be cool.