Spanky,
If you do a chamber cast on your 45/410, PM me the dimensions and I will turn you some 410 plastic/brass hulls to try. I will just neck turn, it will be up to you to load them. I would also need the dimensions of the bullet you are planning to use. FWIW, all 410 hulls are not created equal, some of the winchester hulls, with a proper chamber, can handle well above SAAMI 410 pressure specifications. I don't think you will have any problem with the 410 brass/plastic hulls if you stay within the pressure limits of a 410 shot/slug load or a factory 45LC loading.
BB