by pitted bore » Thu Jul 02, 2009 7:04 am
lokent_72-
You're absolutely correct about Hornady's failure to describe proper usage of the crimp die. They put the standard leaflet for 3-die sets into the box. The use of 4-die sets is not frequently described in reloading manuals, either.
As you know, Die #1 pokes out the primer and scrunches the case. Die #2 brings the neck back to proper size, and also puts a flare on the case mouth. It should be set to provide the minimal flare to allow your bullets to be seated without messing up the case or bullet base.
Die #3 seats the bullet, and should be set so it does not apply a crimp at the case mouth. It's unclear why Hornady put a roll-crimp shoulder in the seating die for a cartridge that should not be roll crimped. Use the part of their instructions that describe seating without a crimp.
Die #4, the one you asked about, is used to remove the flare you put on the case with Die #2 and to press the case mouth into the bullet slightly, forming the the taper crimp. If the case does not enter Die #4 far enough, the flare is not removed completely, so the case will fit the chamber poorly and might cause some feeding hang ups.
If the case enters Die #4 too far, two bad things can happen: (1) the case mouth is pressed too much into the bullet, distorting the bullet, and (2) the mouth of the case is reduced too much in diameter, which could perhaps allow the cartridge to enter the chamber too far, causing multiple other problems.
You should screw Die #4 into your press so that at the top of the ram stroke, the cartridge enters the die far enough to produce a case mouth diameter of between 0.4740 to 0.4800 inches.
If you haven't already done so, you need to get Hornady's drawing of the case with SAAMI dimensions. It's posted on the web on the thread of the calguns forum; find the post from jagermaster on 07-17-2008.
If I've gotten any of this wrong, the pros should be along soon to correct me and provide proper advice.
Good luck.
--Bob