RavenVT100
Member
- Joined
- Aug 18, 2004
- Messages
- 1,107
There's an issue that has revealed itself after buying an RCBS precision mic that I'd like some clarification on if possible.
The precision mic measures the deviation between minimum spec headspace and what your cartridge's headspace actually is. This allows you to knock down the neck of the case just enough to chamber a round in your rifle, without creating an excess headspace situation.
The precision mic reveals that my full length dies actually knock the headspace down to approximately -0.003" under spec, which is slightly more headspace than even a factory cartridge. I am able to raise the SB die (the X-Die, actually) so that I get around +0.001" from spec, which is only 3 thou under what the cases expand to, but in the process of doing so it removes the "camming over" action from the die.
On top of this, RCBS says don't use the precision mic for full length dies, and that the dies always have to "cam over."
What gives?
The precision mic measures the deviation between minimum spec headspace and what your cartridge's headspace actually is. This allows you to knock down the neck of the case just enough to chamber a round in your rifle, without creating an excess headspace situation.
The precision mic reveals that my full length dies actually knock the headspace down to approximately -0.003" under spec, which is slightly more headspace than even a factory cartridge. I am able to raise the SB die (the X-Die, actually) so that I get around +0.001" from spec, which is only 3 thou under what the cases expand to, but in the process of doing so it removes the "camming over" action from the die.
On top of this, RCBS says don't use the precision mic for full length dies, and that the dies always have to "cam over."
What gives?