Like all the rest, I've used W296 and Alliant 2400, but I have also experimented with Power Pistol, and got it to cycle with a Lee C309-120 boolit. Warning: Power Pistol is too fast, in my opinion, for jacketed projectiles to cycle the action - but I have NOT tried it (too scared) as I would expect a pressure spike.
With the gas port pretty far from the chamber, small powder volume and light projectile your powder options are going to remain 1 (maybe 2) step from W296 in speed. heck out the data here: http://castboolits.gunloads.com/show...-in-M1-Carbine
when I plug in that load to QuickLoad, I have to bump it up .5 grains to get the measured velocity of 1750fps. It tells me that 7.5 grains of Power pistol yields 28600 psi at 1750fps, well below the 40000 max. QuickLoad tells me that when I change to a Hornady Jacketed soft point 110 projectile, the pressure goes up to 38000 psi with 7.5 grains of Power Pistol giving only 1830 fps, which is way to close to max pressure for me, and still under normal speed. Tells me I need about 28500 psi to cycle the action (at the chamber pressure). Quickload tells me that is 6.5 grains with the jacketed SP, at 1650fps. Since my field test showed that my lot of PP is more energetic than QL thinks it is, 6.0 grains would be enough to cycle the action.
Don't do this, this is my data only, cannot be verified, all the other warnings!!