I can vouch for the quality of the RD molds and sizers. They work great!
But this particular bullet is designed for the Marlin 1894FG and will not chamber in a lot of 41 Mag revolvers due to the diameter of the nose portion.
My experience with my personal guns:
Ruger Redhawk: Works great
Taurus Raging Bull: Works great
Ruger Blackhawks: Depends on which one, generally will not chamber or chambers with difficulty.
S&W 657: Will not chamber
The above is using the bullet sized to .411" (the sizer included in the package deal) and seated to the crimp groove.
It is a good mold, but I don't want people to order this for their revolver and be disappointed and then have a negative view of RD products.