My dad worked up a load that shoots well under 2" with the rough iron sights on both our 1895 Marlins.  405 Lee mostly WW lead, I forget what he is using for lube, (bees wax base home brew recipie from Cast Bullits) over a near max load of 2400.  You don't have to ask if it went off, but I set down and shot over 50 through the pair of rifles one day and did not feel any worse for the wear.  With decent sights, I feel they both would shoot MOA easily with that load.  Only rifle I own that shoots that well with factory Remington ammo too.

few chambers were ringed using 2400 with a wad on it.  A fellow in Poulsbo ringed two Sharps rifles with it in one day. Five shots each. That may be why most shooters dropped it.  Bill Crane has shot thousands of rounds through his trapdoor with 2400.  Bill didnt use a wad.

Joe 
t
The majority of my 2400 use has been in bottleneck cases and have found no need for a wad or filler. With the 45/70 the wad is the problem not the powder. I have not found it to be position sensitive in large cases. I also use magnum primers. That may be part of the solution. I got a lot of real good advice early on.
Tom