There are enough artillery pieces 155mm around in NATO storage to send at elast 300-500 of these to…

....and at the time numerous ZSU units must hold the line without any artillery support at all, not everything 'must' be 'superior'…

There are enough artillery pieces 155mm around in NATO storage to send at elast 300-500 of these to Ukraine. This is simply not done.

....and at the time numerous ZSU units must hold the line without any artillery support at all, not everything 'must' be 'superior': measured by its range, 'even' the M777 is not 'superior' to the mass of Russian artillery.