You will need to try some samples to see what your gun likes. Brands like H&N, NSA and others. Good luck and by the way, you will need to push these slugs at least 850 fps and up.
Depending on what weight you are wanting to go with, but I know the Daystate Howlers .22 20gr slugs are great for those rifles (made by NSA). You might also give NSA a call and see what he recommends for that rifle. He has some good knowledge.