Try and locate some older manuals for cast bullets. I had many years ago a Lyman manual that had a number of loads for 130-150gr bullets for .30 Carbine.
If you are loading for a gas operated semi, the subsonic load won't work unless loaded with a heavy bullet and slower burning powder. I've had modest success with a 150gr bullet in 7.62x39, (used data from C.E. Harris to good avail), but have never taken on the .30 Carbine. I would hazard a guess the either H4227 or possibly SR4759 or XMP-5744 will be the better choice. This is based on loading cast bullets in .22 Hornet, .32/20, and .30/30wcf to accomplish much the same goal.
A formula for determining what impulse level you're looking for is to multiply nominal velocity times the bullet weight. Then divide the weight bullet you're contemplating into the product and the figure you get will be the velocity needed to get the same energy impulse.
IE: 1,900fps X 110gr = 208,999.98
208,999/155gr = 1,348fps
The .30 Carbine will actually function at a lower velocity, so I would suspect that a Lee .311-155GC-Ptd if seated deeply enough over enough H4227 would probably work, BUT USE EXTREAME CAUTION !!!!
The above reciepe could/can result in some extreme pressures if not approached cautiously and from below levels that will initially function the gun normally.
FWIW; Lyman used to produce a mould for a 130gr flat base pointed design explicitely for the .30 Carbine. Seems that I remember a gunsmith that I knew used this bullet and either Herc. 2400 or either Imr or H4227 to test .30 Carbines he had worked on. (Cheaper even then in early '70's than using up hard to come across ball ammo before the Yellow box UMC and White Box Winchester ammo came into being.)
Good luck with your experimentation. Also try contacting Accurate Arms as they may have the data available for XMP-5744 but just haven't chosen to publish it due to lack of percieved interest.
