I am new to reloading pistol rounds and I am loading 10mm auto for a Glock.

My question is I have the Hornady 3 die 10mm die set and do I have to use the expander die and how do I adjust it? I read the manual on it but just never have loaded using one. I know it flares the case but how much should I flare if at all. Thanks for any help

Thanks, Ranchdog

The expander die "bells" the case mouth to ease bullet seating. Adjusting is a trial and adjust sequence. Your die set should have specific instructions included.
But generally place a resized case in the press's shell holder. Run the ram all the way up. Now screw the die down until you feel the die engage the mouth of the case. Run the ram down a bit. Turn the die in another 1/2 revolution. Now run the case all the way up into the die. With draw the case from the die and take it out of the shell holder. Try starting a bullet into the case mouth. The base of the bullet should enter the case mouth without too much flare of the mouth. If the case is flared too much, adjust the die back out a bit 1/16 or 1/8 of a revolution. Try a new case. Repeat until you are satisfied. This is where experience will tell. Too much "bell" and you work harden the case mouth and likely shorten useful case life. Too little "bell" and you can damage the base of the bullet or crush the mouth of the case.
It is not rocket science but it does take some patients.
Hope this is some help.

muck