NEVER, NEVER, mix fast burning pistol powders like 2400 with large volume cases without some sort of overpowder wad, for if you do, you too could experience a debacle.I have not mentioned this for several years, although I'm away I have written about this strange and complicated phenomena.
Using very light powder charges in high-capacity cartridges may, under specific and bizarre circumstances, subject your firearm to a loud, disconcerting, and very expensive KaBOOM! moment.
Rather than to attempt to explain it, I direct your attention to the link at the top of this page.
(Essentially, instead of a steady burn as the ignition works its way through the powder column ... ALL of the powder charge ignites "all at once", which presents a dramatic pressure spike beyond the usual. Your firearms may very well not be sufficiently sturdy to resist this PRESSURE SPIKE!)
But don't take my word for it. Go, RTWT!
PS: Again, I highly recommend The Reloading Pages of M.D. Smith