data from Lyman for the 400 grain Snover  

4759     start 17 grains    1140 fps        8900 cup
             max  21 grains    1373 fps       17,900 cup



I shoot the very strong Browning 1885 High Wall and I have used up to 23 grains with this bullet.  The lighter loads left large unburned or partially burned grains of powder (4 to 8) in the bore. At 22 to 23 grains the unburned grains disappeared. 

I also have a 325 gas check for the 405 Win that is undersize at .410 so it fits my rifle well.
I load that bullet with 25 grains and get excellent accuracy. Groups are near 1" for 10 shots at 100 meters. 

I get excellent results with Federal #210 primers.
My ammo shoots the best with annealed Remington 45-70 brass formed and trimmed to 2.125 long.  Starline brass is too short at  2.100. Starline is way too hard too, unless you anneal it. You may get a ring of lead stuck to the case mouth with the Starline when you extract the empty cases from the chamber.

40-65 brass is a pain to form unless you have intermediate dies to take it down in .020 steps   

Somewhere between 19 and 21 grains of 4759 worked for me when I could get the stuff, 4227 is a no go if you want the best of accuracy. I replaced the 4759 with 5744 and the powder weights remain the same. I use no wads and and any primer will light the powder, just don't look down the barrel, the amount of fouling will scare you but it shoot's good just the same. If you can't stand the high cost of 5744 try RL-7 or Accurate's 2015, around 24 grains shoots almost as well as 5744, good luck.
I will add that the above loads are used in a fixed case but figure they would be a good starting place for breech seating.

Good stuff here.   I've got a Marlin 1895 I'm casting a 317 grain bullet for.    Also got the Snover and a recent PJ acquisition for two single shots.    I have luck with both 4198 and 4759.    Bought it everywhere I found it for a while.   Still to cheap to pay gouging prices.   I've seen it here for as high as $35.   That's way above the threshold Economists call the point where folks turn to a substitute.  At least for me!  Nearly everything I've read about 5744 is good in that respect.