It really could be because the 480 Ruger can be loaded with bullets seated out, with the only limitation being the length of the cylinder over all. If that is available, there is no loading difference between 480 Ruger and the 475 Linebaugh.
It is just like a 44 magnum bullet with a crimping groove set to maximize the available space in a Ruger Redhawk revolver cylinder. It effectively is putting the weight outside the case and that allows more powder to be available inside the case. Just my opinion though.
Dittos, though IMHO 400 gr @ 1200 fps isn't too shabby and that's where I load my 480 at. With 475 length bullets you have might find you get better accuracy due to the smaller powder column being friendlier with those "milder" loads.
While I have loaded the 480 to 1300+ with 400's, the felt recoil increases significantly.
The 480 as is has always been what I wanted, a shootable big bore revolver.
