I've got a #1-B which has been rebarreled to .405 ( 24" tube ) and I go a bit hotter than the Hodgdon's data with Varget to get @ 2,050fps with the 400gr Woodleigh soft. After that point you can't get enough Varget in the case to make a difference. A quicker powder might do it but I get sub-inch groups at 100yds, works for me. FWIW, I worked up my data before Hodgdon published theirs.

A fellow who posts on AR as Robgunbuilder says he opened up the throat of his Encore in .405 to take a bullet loaded 0.25" further out ( if memory serves ) and he claims to get 2,150 fps without pressure signs. Might be practical with the #1 if I needed a couple hundred extra fps.

I've seen data for the "Tropical" loading for the 450-400 listing 1,950 fps for a 400gr bullet intended for high temperature use. And I believe I've seen postings by people who actually chrono'd 450-400 ammo state that the actual velocity was a bit under the "2,150" claim from real double rifles.

confused yet?

My rifle has fired one ( 1 ) shot at game and that Woodleigh sailed through the lower chest of a Blue Wildebeest bull at about 40 yards. He galloped about 25 yards, collided with a tree and was down for the count (sounded like a car wreck!).

Short answer is IMHO your #1 can be loaded to kill anything you should chase with a single shot rifle, it's not a 450-400 but the animals won't know the difference.

hth

Rick