I've only shot paper with that calibre
and still own a 450/400 3 1/4".

I doubt it would be any difference to the
3" version. I am in the camp that at the
end of the day, it is a 400gn bullet at say
2150 fps, what cartridge it comes out of
is kind of irrelevant.

I would have used 400gn Woodleigh RN SN
if i had used anything. That was what I
used to sight in the gun.

I like the calibre, I prefer the 3" version
only because it is easier to handle in my
hands but I think the 3.25" cartridge looks
sexier.

But that is just my HO !!!

Edit
The gun I was referring to is the Lancaster Sidelock
- known as the "Wrist breaker" due to it's spring cocking
system that made it harder to close for some.
It's on Champlin Arms web site.