- Oct 5, 2012
No, you iron out the dents on the inside of the case necks with the mandrel and then size to taste as normal with the proper bushing. The mandrel should expand them enough so that your sizing die will squeeze them back down. The expander mandrel fits in it's own holder....not in the reloading die. I don't bother with the mandrel unless the case mouths get dented...like ejecting cases with thin necks in a 1k match that has a concrete floor and your brass misses the brass catcher. I cringe every time it happens!!
The mandrels I use are more for neck turning. They come in two sizes for each caliber...an "E" expander mandrel and a "T" turning mandrel. The "E" is slightly oversized so that when you are turning necks the brass doesn't fit so tightly on the "T" mandrel, which makes a pile of heat due to friction. Also, the mandrels have a very gental slope to them so that it is easy on the brass. I also use them when creating false shoulders on new brass for a wildcat....like the dasher. Run the .257 "E" mandrel into a 6mm BR brass, then neck it down the proper amount with your regular realoding die and POOF...instant false shoulder.
I know mandrels are a separate die. So if I have a 284 spent case and put the mandrel through it nothing will happen b/c the shoulder is already blown beyond .284, so do you neck size then open it w/ the mandrel? If you do, how do you determine your neck tension? Also over time your necks will thin and changing mandrels isn't as easy as changing bushings.
I guess I'm a little confused on how to use a mandrel for reloading, I've used them to open 6.5 to 284 and thats it. At one point I did want to use a lee mandrel but after talking to a guy who is far more meticulous than I said what he does to his mandrels w/ honing etc.... so I aborted.