Quote Originally Posted by Thegreg View Post
Measures .220" which must be undersize surely. I'd expect this to measure about .223" to allow the brass to contract back down to .222". I don't have another one to check and compare but will order a new expander tomorrow anyway.

Cheers
Greg
It does seem a bit undersize, on various dies that I have had the expander has varied between .221 to .223, apart from Lee collet dies which had a .220 mandrel as they are squishing the neck onto a mandrel rather than using an expander to push a neck out that has already been undersized by the die.
Too much neck tension is usually avoided, but..., if the ammunition that you are making gives good accuracy with that degree of tension, I would probably take a little material off the trimmer pilot so that it fits the neck.

Many knock Lee stuff but I have been quite happy with the results from collet neck sizing dies.