I had terrible service from NEI. I waited several months with no responce to emails and when I got it the hollow base pins on the mold were horribly cut and needed to be reworked on a lathe. This was for a .41 Colt hollow base. I do not recommend them, do a search on the Castboolits forum.
I have bought from Bernie at Old West and he was great. Excellent mold (.44WCF with hollow base). Bernie makes five molds for the .41 Colt, ask him for the specs.
My favorite for .41 Colt is the Rapine 386184. I bought mine new just as the company shut down unfortunately. I bought two more off the EE and Ebay. I love the way the hollow pins stays in place on these molds, very quick to cast. It sucks they are not made anymore.