Duff-Man wrote:OldmanFCSA wrote:I prefer Redding Dies, but RCBS and Hornady dies can be accurate also.
If you use a universal de-capping die, then I modify the sizing die to put expander up near neck in sizing die. Lube case, inside neck and outside, stroke case up into sizing die, adjust expander rod up until it contacts brass inside neck of case, screw down 1/2 turn and tighten lock mechanism while holding withdrawal tension on it. This will give you very close to zero run-out of case neck to body. Case neck will be expanded while still in neck of die holding it centered, last little bit of neck will follow first part. Of course this method requires no variation of neck wall thickness to be most accurate. (I neck-turn my target brass for best results.)
Feel free to contact me for more info if needed.
Is this info in a book? If not you and Sam need to write a book.
Actually, it is explained here:
http://www.forsterproducts.com/store.asp?pid=36197 in the lower diagram on the right...
Oldman's explanation is 100% correct and less words than I could do, and this isn't a new concept. I learned about it because of the Colt AR-15 SP1 I bought NIB in 1975 for $125, and had to buy reloading stuff for it. Got a Bonanza (from Faribault, MN...) benchrest loading die set with a size die set up this way, so I knew about this back then. Went through utter misery with a Redding Type S neck die and a never to be sufficiently damned Lee collet die
http://leeprecision.com/reloading-dies/rifle-dies/lee-collet-dies/ with my .338 Ultramag, and could not get my loads concentric to save my soul. the Lee die is particularly evil, in that it is very simple and looks to be absolutely foolproof and HAS to produce concentric neck sizing, but it pushed the neck of my cases up to 5 mils off center, and I spent the better part of $300 for bullets and powder and runout gages and neck turning equipment to try and make that damn die work. It was all wasted effort.
As far as this knowledge being public, obviously people with other designs either know their product is inferior, or like Richard Lee and the people at CED and Dillon who sell that $140 crappy electronic scale, either do not comprehend how faulty their product is or do not want to believe it. Thus the underground nature of this hard-won knowledge...
BTW - You can get a Redding FL steel die, swap out the decapping stem for a shorter one, and make a Forster type die for cheap provided you have another way of decapping your brass
This is my .338 RUM benchrest die made that way