Managing custom post type columns which have a slug that includes a hyphen

Is there something simple that allows one to manage the columns displayed in the list post admin page for custom post types that have a hyphen in their name.

Eg this works perfectly for post type milestone

function custom_milestone_columns($columns) {
    return $columns;

...but this causes a white screen for post type incident-injury

function custom_incident-injury_columns($columns) {
    return $columns;

Is the hyphen being stripped out and replaced with some other characters as a part of the manage_{$custom_post_type}_posts_columns function?

Thanks - Mark