User blog comment:Sentry 616/Weapon Gushing/@comment-27144409-20190926025347/@comment-27144409-20191020004955

Oh, I'm sorry I never replied. Whoops. I'll explain, and then give you something new to look at in a new post.

MRSI is an Ironically named updated version of Time on Target, which was an atillery doctrine adopted and perfected in WWII by the allies. Based on brutal experience from WWI and some of WWII. The idea is for all friendly artillery assets in a battle to fire at precise angles and times, so that the first shells from each artillery piece all hit the target area at approximately the same time (plus or minus 3 seconds).

Note that this is not the same the same as everyone aiming at the same target. The differing calibers, distances, shell types, and conditions, not just of a single battle, but wherever this tactic was desired. (which I assume to be whenever there was a decent concentration of artillery) No, they had to create complex charts and tables with which to plan out bombardments.

As for MRSI, modern loading technology, specifically partial or fully automated loading, along with computer controlled/assisted firing and aiming, lets a single artillery piece hit roughly the same area at roughly the same time with up to 5 shells. With each consecutive shot, the barrel lowers (and presumably the amount of propellant is adjusted) so that the shells have shorter distances to fly, since the shallower trajectories are shorter paths.