Originally Posted by lastdingo

I disagree. The "per minute" ROF is not so important.
This is all about MRSI (multiple rounds simultaneous impact) - it shoots probably 6 or 8 shells as a system and then runs (shoot & scoot tactic to dodge counter-artillery fire). MRSI is possible due to quick (electronic) calculations and variable propellant (varying quantity of charges) plus pre-programmed change of elevation between shots. Strong charge/high elevation + medium charge/medium elevation + small charge/small elevation yields the same impact point. The shells arrive in a time window of just few seconds.