Snap views are always 320 pixels wide.
This is only true from a developer's point of view.
For the pedantic ones like me: Snap views are NOT always 320px wide. If they were, they'd be only one inch wide on a 300dpi screen. In fact it's Width= (320px * system-supplied scaling factor).
But since scaling is done by the system and a developer doesn't need to care, Andrei is perfectly right.