I ordered a set of full-length Lee collet dies in Ack. Imp.
Not sure what you ordered, but Lee makes a set of FL Pacesetter dies in 257 AI. The also make a "Collet" neck sizing die in 257 Roberts that will Neck size only the 257 AI. I have not seen a "set of FL
Lee Collet dies in AI"?
Got a link to your purchase?