Lobo,
The 414 Super Mag is to the 41 Remington Mag like the 445 Super Mag is to the 44 Remington Mag.
It's a 41mag with brass that's about .25 inch longer. You can find a little more about it on the Dan Wesson web site. silhouette shooters use it most.
Me, I like it because I can load another caliber since I already have the bullets. It uses the same dies as the 41mag, only you use large rifle primers with the brass.
This is where some of my facts may err, Mr E. T. Gates is its designer. The same fellow that designed the 357 Max/supermag.
I was thinking about coverting my new Marlin 1894FG-41mag to this, thus the reason for the initial question. But I've just learned that Marlin is going to produce these this year and stop production. So Unless I can get another, the conversion is on hold.
Now, you know everything that I think I know! LOL