I've handloaded for a few doubles, three 450/400 3" and one 3 1/4". All three of the 3" guns, two old Jeffery tiger guns, all found regulation velocity at close to 2150 fps. I believe this was the original ballistics for the caliber also.
The woodleigh's at .411" solid or soft will assuredly regulate in doubles at about 2150 fps.
I also have a Ruger #1 in the caliber and found 2200 fps to be the most accurate load with RL-15 and woodleighs, I've not tried the Hornady bullets. The Ruger is capable of 400's at 2400 but you may not want that level and it will take a strong bullet to hunt at that velocity. When I scoped this Ruger it gave three shots touching from 100 yards with the RL-15 and 400 Woodleighs.
I'm sure the Hornady data is for safety for the old doubles but nbot necessarilly to regulate and I think they are .410" bullets.
