Slitherine

the rules say heavy artillery doesn't move
the rule says too that tropps behind a fortification turns to face if contacted by flank or rear

so artillery doesn't turn if contacted by flank?

i find it very restrictive that heavy art cannot even pivot

snif

the rules say heavy artillery doesn't move
the rule says too that tropps behind a fortification turns to face if contacted by flank or rear

so artillery doesn't turn if contacted by flank?

They don't turn. It really doesn't make any difference, since ther'es no disadvantage to fighting enemy to your flank - other than the initial DISR. It would actually be worse if they did turn, as that would expose them to a flank charge from their original front.

i find it very restrictive that heavy art cannot even pivot

That's intentional. 'Heavy' artillery was rarely used in battles, and were moved even more rarely. Most didn't have any wheels, so even turning was next to impossible.
The points cost reflects this immobility.