Mikey:
I still can't get over the fact that the bullet company did not provide some good load data for these bullets. You said they're expensive and I don't think you should have to fritter away your money by figuring how to load the stinking things. Can't they come up with anything for you? My minimum expectation would be data for three powders. The only exception I can think of to this expectation would be for 44 and similar cartridges where H110/W296 are THE powders for high performance hunting loads.
My own tendency would probably be to go to a slower powder rather than a faster powder. Maybe Blue Dot or AA5.
I just dug out my Loadbooks USA 45ACP book and here's what I found for bullets heavier than 230 grains. My conclusion: Try some penetration with 260 grain Speer bullets and some HS7 powder.:
IMR powder (bullet, brass, and primer brands unspecified):
800-x powder:
260gr JHP min=5.8gr@730fps/13,800CUP max=6.4gr@790fps/17,100CUP
260gr JHP min=4.2gr@714fps/14,400CUP, max=4.6gr@746fps/17,400CUP
Winchester powder:
231 powder:
260gr Jacketed min=4.4gr@681fps/12,400CUP, max=5.0gr@788fps/16,600CUP
Alliant/Hercules
Blue Dot:
260gr JHP min=7.5gr@721fps/13,100CUP, max=8.0gr@764/15,400CUP
Unique:
260gr JHP min=5.0gr@695/13,400CUP, max=5.8gr@755/15,100CUP
Hodgdon powder: tested in 5 barrel
HS7 powder
260gr min=8.8gr@816fps/13,500CUP max=9.3gr@853/15,900CUP (woo hoo!)
HS6 powder
260gr min=7.5gr@801fps/13,900CUP, max=8.0gr@849fps/16,800CUP
+P load for HS7 with no reduction in charge weight recommended. 5 barrel.
260gr 10.0gr@891fps/19,700CUP (!!! Ya know, Mikey, you may want to try some 260 grainers.)
Speer data for their 260gr JHP. COL=1.200 Primer=CCI 300 Case=Speer, Gun=SIG P-220
Herco powder. Min=6.3gr@775fps, max=6.9gr@847fps
231 powder. Min=5.4gr@756fps, Max=5.9gr@824fps
Unique powder Min=5.8gr@752fps, Max=6.3gr@821fps