I have a question for those who use the expanding mandrels from Wilson, Sinclair, K&M and 21st Century.
It looks like the standard size mandrels are 1 thou or 0.0008 +/- 0.0002" under bullet diameter.
Are those the mandrels you are using before seating bullets?
If so, are you getting 1 thou difference before and after seating? Some people call this "neck tension" or "bullet hold." Is 1 thou enough?
Sinclair describes the purpose of these mandrels as being for the purpose of opening the necks so they can be placed over a neck-turning mandrel.
LE Wilson describes these mandrels as being for the purpose of opening up new brass that is either under-sized or possibly damaged in packing or shipping to "slightly less" than bullet diameter.
Some authors of articles in the Accurate Shooting bulletin have described using the mandrels and experiencing spring-back to 2-thou under with Lapua brass, but not necessarily any or all brass.
I've received the impression that it has become popular to size necks with these mandrels in lieu of the carbide expander balls in full-length bushing dies (Redding Type-S, Wilson, Whidden, etc.) The practice is to push the cartridge into the die to bump the shoulder and squeeze the neck down to a bushing size just below what the expanding mandrel will open. Then the case is pushed into mandrel die where the mandrel opens the neck, sizing the ID vs. the bushing that sized the OD.
I've read descriptions of why the pushed mandrels are supposed to be better than the pulled balls/buttons.
What I want to know from the people who use these mandels for the purpose I just described, is: Are you using the standard size mandrels sized 1 under bullet diameter? Or are you using a smaller mandrel like the ones from 21st Century that are in half-thou increments? If you're sizing 1 thou under bullet diameter, does your brass spring back to 2-thou under? Are your bullets secure?
It looks like the standard size mandrels are 1 thou or 0.0008 +/- 0.0002" under bullet diameter.
Are those the mandrels you are using before seating bullets?
If so, are you getting 1 thou difference before and after seating? Some people call this "neck tension" or "bullet hold." Is 1 thou enough?
Sinclair describes the purpose of these mandrels as being for the purpose of opening the necks so they can be placed over a neck-turning mandrel.
LE Wilson describes these mandrels as being for the purpose of opening up new brass that is either under-sized or possibly damaged in packing or shipping to "slightly less" than bullet diameter.
Some authors of articles in the Accurate Shooting bulletin have described using the mandrels and experiencing spring-back to 2-thou under with Lapua brass, but not necessarily any or all brass.
I've received the impression that it has become popular to size necks with these mandrels in lieu of the carbide expander balls in full-length bushing dies (Redding Type-S, Wilson, Whidden, etc.) The practice is to push the cartridge into the die to bump the shoulder and squeeze the neck down to a bushing size just below what the expanding mandrel will open. Then the case is pushed into mandrel die where the mandrel opens the neck, sizing the ID vs. the bushing that sized the OD.
I've read descriptions of why the pushed mandrels are supposed to be better than the pulled balls/buttons.
What I want to know from the people who use these mandels for the purpose I just described, is: Are you using the standard size mandrels sized 1 under bullet diameter? Or are you using a smaller mandrel like the ones from 21st Century that are in half-thou increments? If you're sizing 1 thou under bullet diameter, does your brass spring back to 2-thou under? Are your bullets secure?