These two places say that everything is availiable
Brownells:
Fits Apex Muzzle Loader; CVA All Round Barrel Models; Traditions Round Barrel; Remington Genesis Muzzle Loader; Win X-150
947-000-163
Maxima Base Set, Polished $23.75
947-000-164
Maxima Base Set, Matte $23.75
947-000-213
Maxima Base Set, Silver $26.65
Midway USA
Warne Maxima 2-piece Weaver Style bases
Blue 593402
Matte 750848
Silver 996237
I like the Weaver style steel bases, and Warne is one of the best. Couple those with the Burris Rings that have the plastic inserts and you have a fool proof system. Those rings hold like super glue and do NOT mark up a scope.
Hope this helps