Interesting thought given that heavy pellets increase the power output of PCPs and reduce that of springers and the Tempest produces around 3.6ft/lbs with more suitable pellets on a good day
A light pellet such as the Thunderbolt would yield significantly more power from a low to mid powered spring pistol.
Regards,
Nick
Research the real meaning of point blank rather than that associated with poor fiction and even poorer news reporting, it doesn't mean up close