User blog comment:IamJakuhoRaikoben/Chapter 370: Demons Reincarnated, Review./@comment-5598380-20140208004744/@comment-7418318-20140208092621

It's five hundred times, not one thousand.

And we don't know how much "one jupiter" is in the first place. It's possible that "one jupiter" is the minimum output that's necessary to create a stable combination of those four magic sources behind the firing principle or the damage output of the very first Jupiter cannon that was build decades ago, so both the Phantom Lord and the Grimoire Heart Jupiters might already have shot out multiple or even hundreds of "jupiters" or magical energy. To me it didn't look like the two mentioned cannons were of equal power in the first place.

Just like the first cars had one or two Horse Powers and now cars can have hundreds of Horse Powers.