I don't think you can get a BAT "M" with the Chytec bolt face any more. They only show the "L" and the "CT" action available for the Chytec round.
Welcome to BAT Machine Product Page
They don't have a direct link to the page that lists the combos. On this page click on the red "action" tab. After that page loads click on any of the "configure action" tabs on the right...that takes you to the page that lists whats what.