Complex sentence: The smoothbore design of the HDP would enable a much higher rate of fire than was possible with normal guns; the entire battery would be able to fire up to 10 shots a minute, capable in theory of hitting London with 600 projectiles every hour.
Split into simpler sentences: The smoothbore design of the HDP would enable a much higher rate of fire than was possible with conventional guns. The entire battery would be able to fire up to 10 shots a minute, capable in theory of hitting London with 600 projectiles every hour.