You need this adapter for the Kratos
https://donnyfl.com/products/benjamin-akela-1-2-x-20-unf-adapter-a8?_pos=1&_sid=b9aecaef5&_ss=r
Some customers report that the adapter takes up space in the shroud and tightening the adapter pulls the shroud against its set-screws. Removing one baffle resolves this as a potential issue.
I recommend the Sumo for the Kratos.
https://donnyfl.com/collections/ldc/products/1-5-x-6-5-inch-sumo