The collet neck sizers are a good idea, but with 2 out of 4 I have bought, they needed tuning right out of the box. I would polish the mandrel as was suggested and keep it and the crimp die if your set came with one. I own I think 5 of the factory crimp dies. None have given me problems, but as they break in I have had to readjust to maintain a proper crimp. It's lmpossible to get precision when there are tooling marks as bad as I have seen on some of my Lee dies. My brand new Lee 7mm mag FL die caused WAY to much case sticking. Dissasembling it and checking it with a bore light showed why. Shoddy tooling. Lee replaced it with no problems, but I am not going to go the same route with my Lee .223 deluxe 4 die set. I have on my desk a Hornady New dimension 2 die set that will make everything ducky. A quality full length sizer for first time sizing, and a top quality seater. I will keep the Collet neck sizer and Factory Crimp die from the Lee 4 die set, and pitch the Lee FL die and dead length seater. I prefer to own products with lifetime warrantees that I don't have to use repeatedly!