I use old .284 brass cut down to 1.70, not reamed. I use the Hornady sizing die and seating die, no expander, and a modified Lee 45-70 factory crimp die I run everything back through the Hornady crimp die set just to kiss the case mouth back to .480 It never really touches the .284 brass, but it does smooth the flare off the mouth of Hornady brass that's gotten short to the point that the "waist crimp" is right at the mouth. I shot 50 rounds of .284 brass today with no isses at all. The photo attached is the best load I found using the 225 FTXs over 297, a one inch 5 shot group at 100 yards, ( 4 shots stayed in .6 inch). One other difference is that I'm seating the 225s longer to 2.245. My rifle has enough throat for this and they really do shoot well seated out that long. The limitation on my rifle currently is the trigger. I think there's a RRA 2 stage in my future.
BD