Re: rcbs gold medal dies or redding competiton dies
I just borrowed a friend's .223 RCBS Small Base X Dies. I was surprised to find that even with a conventional expander ball, the neck runout on a sample I took was between .001"-.002".
I think that most companies that have invested in modern CNC machining equipment are now turning out dies that are excellent. None are standing out as obviously superior. Even non-match grade dies are turning out great ammo.
I also own Hornaday New Dimension and Redding Match / Regular dies and frankly can't tell much quality difference between them in the form of loaded ammo.
I've also found that I have no use for micrometer heads. After I find a seating depth I like for a specific bullet, I just create a dummy round and file it away as a seating depth gage. If I reset the dies, I just back out the seating stem, put the gage in and ram in the uppermost position and lower the seating stem until it hits my gage.
I do have a used die set that looks about 15+ years old and the runout on that is definitely not up to par with recently manufactured dies.
--Rootshot
p.s. I used to have an RCBS set with the bullet seating window when I first started reloading. I quickly found out that this is an unnecessary feature that really doesn't add anything except another specialized shellholder.