.450/.400 3" N.E. Cast bullet loads?

[.22-5-40]

Hello, Sir, I was wondering if you would have any cast bullet load suggestions for this caliber.  I'm looking for mild recoil, accurate 100yd. loadings.  Was thinking of 300gr. to 400gr. plain-based bullets?  I have used smokeless in a .40-70 straight Sharps.  300-385gr. plain-base, with 1/16" fibre wad under bullet base.   using H4895, Varget, AA5744...I wonder if this big case can be treated the same?  Thank you!

[Veral]

  A very good question, which I'll answer for all large rifle cases, regardless of caliber.

 There is no reason for concern about performance of a large cartridge with low recoil cast bullet loads if fast burning powders, which are easier to ignite than slow burning powders, are used with magnum primers.  Best primer is probably the Federal 215, as it will lay the hottest blaze possible over your powder, which will be pretty much laying along the length of the cartridge.

  If you do find velociities erratic, the problem can be easily solved by choosing a powder that fills the case at least halfway and fillering with granulated plastic shot buffer to the top of the cartridge.  This will be compressed when you seat the bullet and hold your powder tight against the primer for very positive ignition.  The only reason for a half case full of powder is that some report accuracy falling off if too much buffer is used.  It is not dangerous to use smaller charges of powder and the rest buffer,  as long as one takes every precaution that he doesn't double charge the powder.  i.e. Fill all the cases, check powder depth of all, then fill with buffer and seat your bullets.  If the huge wad of buffer causes inaccuracy, go to a load with more powder to reduce the buffer stack.

[32-40win]

Realizing this is an older post, it is still worth putting an answer to IMO, as the info on cast boolits and  the 450/400NE is scattered and takes a few different searches to acquire.
I have a Ruger#1, in the 3" version. Got two moulds from Veral last year, a 320WFN and a 400LFN.
Both cast WW at about .4125. I have to size the noses to .410 to be able to chamber them using the crimp groove, .411 results in having to semi breechseat them. Both were cut for Gator gaschecks.
Used Hornady brass, CCI250, AA5744 and the 320gr to start with, got the data from Western Powders. I settled on a 48gr load, chrono'd @ 2041fps. I did switch to an F215, after having some FTF's in the first batch I ran. It was the primers fault.  I've shot about 120 rds of that load so far, and some 400gr which spilled from the container at the range and got mixed up in load order on the initial charge test batch. They ran up to the high 1800's with those loads.
The recoil on the 320's is minor, the 400's mild compared to factory Hornady 400's. I shot 48rds of 320's the one day, no pain , no suffering. And they shot well.

I definitely recommend running cast in the 450/400NE, it's fun.