For a book; Lyman cast bullet handbook. Online; Hodgdon powder lists 4 powders to use.
My 38-55 High Wall is a modern Winchester (ca.2005) and I use .377 cast bullets.
I really like a trail boss load that produced a 20 shot dime sized group! (Lyman tang and #17 globe sights, off a rest @ 100 yards). When Trail Boss first came out, there was no/little loading data so they told you how to best load it!
RULE 1, NEVER COMPRESS Trail Boss!!!
To start, look at your bullet, and find the crimp groove (if smooth, determine seating depth into case. You want Trail Boss to have a gap of 1/16" to 1/8" under the bullet. Weigh that powder charge & set powder measure.
My load is for 1/16" gap with 255 grain FP Bear Creek coated bullet .377, WLR primer Winchester brass. That Cartridge overall length measurement will very according to brass length and bullet depth. Est. Velocity 1300 fps.
Starline makes two lengths of brass, won't make a difference on smokeless loads, unless you mix them!
The most common bullets are flat nosed, for lever actions and are fine out to 200 or so yards. but for long range shooting (300+ yards) you will want a Round Nose (Lyman makes a Ballard designed by Harry Pope, 310gr that casts to 330 in pure lead,) or a Spitzer or Semi Spitzer.
Modern guns can use jacketed bullets safely, but for superior accuracy use a soft lead alloy (Wheel weights and type are too hard!) and stick to Black Powder Velocities (less than 1500 fps).
The cartridge was a target round invented by Ballard, from the late 1870's or early 1880's. Marlin bought out Ballard, and Winchester stole the round and renamed it when they went to the flat bullet in 1894. (in earlier High Walls the called it a 38-55 Ballard) If you keep it to target velocities, you can be amazed what a good rifle/load combination will do! (I know I was!)
Harry Pope really liked 38-55 and set some shooting records with it, until he fell in love with 32-40, and smashed every applicable record with that. His 200 & 300 yard offhand records still stand! (for 100 round & 200 round groups! The Offhand 200 yard 200 round group is just over 3" with peep sights! 32-40 still reigns in Schutzenfest!) The European name for 38-55 is 9.5x51R or 9.6x51R depending on the manufacturer.
Ivan