Unfortunately the Lyman 'Plains' bullet mold is not the same as the Hornady 'Great Plains' bullets which are both hollow point and base.I believe lyman has an exact mold for this bullet!
Their hollow base Minie ball mold is actually closer to the design of the Great Plains bullet.
The Lee .54 cal hollow base improved bullet mold looks pretty attractive however and a LOT less than the Lyman mold.
I 'may' start casting again.