Burch-
My 45 Colt dies are RCBS. Your procedure sounds fine and that load should work great like Longtom said.
If your cases fit the cylinder before you loaded them, then they should fit after you load them - unless you are somewhat changing the shape of the case while you are loading?
I haven't done the 45's yet - I forgot to pick up the 44 dies needed to crimp the top gas check into place. It will need to be a 44 gas check, also, not a 45. 45 gas checks won't fit inside the cylinder throat no matter what you do. With my 41mag, I used 38-40 crimping die, which I just happened to have. Are you expanding with a 45 expander? That's a no-no - too big for the throats. If you did do that, just run the top of the case, maybe a half inch or so, as necessary, to let the case fit into the throat area. If you trim the case shorter to make it fit, you might just as well use standard 45 cases? Use the 44 dies and let the case fireform to fit. These 444 cases I just trim to length desired, stick in the powder, add gas check, stick in the shot, add gas check, crimp with 44mag crimping die - which I forgot to pickup so this is on hold. Expect enough pressure to properly fireform. All future loading will have to be done with 44 dies, as well.
The old Lyman manual shows standard rifle primers for cast loads with Unique and 2400 and so I think I would stick with that - the standard rifle primers. It's one more thing we can play with in this development process. Maybe load some with Pistol primers and note the differences, if any.
Hope this gets you up and running - this has been a fun trip for me.
Regards,
Sweetwater