28gr of 4198, with a 405cast chronos at 1200fps. Out of a CB.
You may want to try Universal Clays, as well as Unique. Either powder, the "sweet" spot will be between 13 or 14gr. 14gr of either powder will yield 1100-1150fps with a 405. Out of my CB, the 350's shoot better at 50yds. However, the 405's are shooting 4-1/2" to 5-1/2"@200yds. The 350's are going to 10"@200yds.
No filler needed with Unique/Universal Clays. Have fooled with fillers in the 4198, waste of time. The Universal Clays has single digit extreme spreads.
Will work some 405's up with H 322, in the near future.
Bunch of load data in this thread, was working up the CB. http://www.marlinowners.com/forum/45-70-govt/78432-1895-cb-skinner-sight.html
Hope this helps.