No, you don't need to expand the case mouths. Use a de-burring tool to lightly chamfer the inside of the case mouth.... just enough to remove any micro burrs, and to put a very slight bevel on it. This will allow the bullet, even plain based, to enter the mouth of the case.
Nearly all rifle reloads rely on the tightness of the sized neck to friction hold the bullet in place.
If these are to be fired in an autoloader, you might consider a light crimp on it after the bullet is seated.
I use a Lee factory crimp die on mine, and it works wonderfully well.
If it's for a bolt action, I wouldn't crimp them at all.
Same thing goes for the hornet.... use the de-burring tool to put a light chamfer on the inside of the case mouth, and seat the bullet slowly.... you'll get the "feel" for it pretty quickly.