Critting with a spell storing weapon.

[Lord Pendragon]

Spell Storing

A magus wields a spell storing scimitar (threat range: 18-20 x2) containing an intensified shocking grasp.

The weapon crits on a roll of 19, and casts the intensified shocking grasp inside. Is the spell a crit as well?

The weapon crits on a roll of 20, and casts the intensified shocking grasp inside. Is the spell a crit as well?

The question comes from the fact that the ability states that the weapon casts the spell, not the wielder. Therefore I am wondering if it still gains the critical threat range of the weapon, which is a magus ability gained when using spellstrike, or only uses a spell's innate ability to crit, which would only be on a 20.

[DeltaOneG]

It almost reads like you'd make a separate attack roll for the spell if the spell requires an attack roll.

Not sure and that seems clunky and unintended but since it's an actual casting of the spell (as a free action, but still a casting).

I'm not sure what RAW is but I'd guess the spell will crit only on a nat 20, but not require an extra attack roll.