From today's Bulletin... Just wanted you guys to stay safe:
OBSERVATION and WARNING
Berger may definitely be on to something here, and we applaud Berger’s testers for testing a very broad range of seating depths. However, we want to issue a STRONG WARNING to reloaders who may be inclined to try the 4-step method listed above.
Be aware that, as you load your cartridge progressively shorter, putting the bullet deeper into the case, you will be reducing the effective case capacity dramatically. With smaller cases, such as the .223 Rem and 6mmBR, moving from .010″ into the lands to .080 and .120 off the lands can CAUSE a dramatic pressure rise. So, a load .010″ into the lands that may be safe can be WAY OVERPRESSURE with the bullet is moved .120″ off the lands,i.e. .130″ deeper in the case, the difference between .010″ in and .0120″ out).
To illustrate, using a QuickLoad simulation for the 6mmBR cartridge, moving the bullet 0.130″ deeper into the case can raise pressures dramatically. With the Berger 105 VLD seated .010″ in the lands,with 0.220 of bearing surface in the neck), and a charge of 30.0 grains of Varget, QuickLoad predicts 60,887 psi.,This is using ADI 2208 data, and a 5500 psi start initiation value). If we move the bullet back 0.130″ further into the case, QuickLoad predicts 64,420 psi,even after we drop start initiation pressure to the “default†non-jammed 3625 psi value). The 64,420 psi level is way higher!
Cartridge & Load COAL Jam/Jump Start Pressure Max Pressure
6mmBR, 30.0 Varget
Berger 105 VLD 2.354″ 0.010″ JAM 5500 psi 60,887 psi
6mmBR, 30.0 Varget
Berger 105 VLD 2.224″ 0.120″ JUMP 3625 psi 64,420 psi
NOTE: This is only a software simulation, and the real pressures you encounter may be different. But, the point is that moving the bullet 0.130″ further down in a 6mmBR case can raise pressures more than 3,000 psi! Therefore, you must employ EXTREME CAUTION when moving your bullets that much in a relatively small case. Remember that going from .010″ jam to a very long jump will probably increase pressures in your cartridge so you MUST adjust your load accordingly.