The "neck" that you describe may actually be the pilot, and yes, the pilot is needed. If you are describing a neck reamer, then it is not needed for a basic setup. You will also need a collett--read the specs as each collet has more than one step and fits a number of cartridges. Try to buy the collet that fits most of your calibers, then buy 1 or 2 extra, if you need, to complete the lineup.

Get the little adapter so you can run the thing off of an electric screwdriver. Life is too short to get carpal tunnel from twirling that itty bitty handle. Forster is located in Beautiful downtown Lanark, Illinois. I stopped in on day when I still lived in those parts. Very nice people. Give 'em a call, tell them what you want to do, and they'll sell you just what you need.
JCN

Purchased a used trimmer (Forster) without accessories like collet and pilot, is the neck a necessary part, too? (Their website shows neck #308 for 30/30 and # 355 for 9mm). Thanks for any assistance. I do have hex wrenches!