Measured both a factory 200 gr Hornady 450 B and a new Hornady brass piece with a Hornady 250 bullet at 0.4765"( how's that for a bunch of whole bunch Hornady's)...AND a 275 gr Fury cannelured/serrated with the same numbers.
This being a round that supposedly headspaces on the case mouth, but also with a tapered case you just have to be careful how much FCD you attack loaded rounds with. Lee FCD's can really put the hurt on everything except a solid mono-metal bullet...I don't want to get into that Sturm und Drang over 9mm and 45 and other mouth headspaced cases...been there, done that, it's over...for a very long time....I squeeze it just enough...what that "just enough" is you have to work out your self...I'm not all that convinced a crimp is needed for this cartridge, but I won't argue that point, it's not worth it...do what YOU think is best for YOU. I might do some testing in the future, and there is a ton of information on just that process already out there for all kinds of cartridges, so why keep reinventing the wheel...read the data, decide what to do and do it or don't.
First thing I do to Lee dies is get rid of that morpho-dyte "O" ring POS and replace it with a "normal/standard/every-other-die lock ring because I have Rock chucker and a Forester presses and rubber isn't conducive to accurate ANYTHING. After that it's a simple thing to adjust and lock in your dies if needed.
A couple of asides...I HATE buying dies so I use whatever will work and whatever is on sale, don't care WHAT the name on the thingy is...a 45-70 sizer will work for sizing...depending on your chamber specs and the amount of brass expansion...so will the seater possibly...you might have to do a bit of chewing here and there tho'...and 45 Colt revolver and 45-70 taper crimpers will also work depending on how cheap you can get them and how much chewing you are willing to do to save a buck. I have quite a few 45 cal toys from 45 ACP to 45-120 so depending on what I'm loading I mix and match from many dies sets...and note which and what die gets used where and when.
I'm going to enjoy this little jewel...not a lot of recoil and a WHOLE LOT OF FIREPOWER at the touch of the go button...hahahahahahahahahahah
Luck