I just started loading 22 hornet. I am just coming into the learning curve on this nifty round.
One of the issues with this is that because of the slow twist on the barrels, it keeps you limited to bullets of around 50 gr or less. The consequence is you will probably only find flat base projectiles. Not a big deal except the necks are so thin that any mis-alignment and you will crush the case.
I know there are flare dies for this and I have one but have had limited success with it.
An idea hit me....
My RCBS Trim Pro was set up for trimming 25-06.
My thought was to use the guide mandrel for .25 and use it to open the case mouth just a bit. Actually works very well. Use it like you were going to trim but the spin the handle and you can actually see the mouth of the case open up slightly and the turning action keeps the neck round.

My dog gives me the bird!