Thread: Trying something, Eric Cortina method of load development

With the neck tension, bullets, and chamber leades where I've tried this, there has been 1mm of base-to-ogive difference in length between jammed and just touching. Backing off 20 thou (0.5mm) from jammed seems quite a large safety margin for range shooting, and would halve the available length settings I have to experiment with if wanting to keep the bullet in the lands. At the other end I also try to avoid getting too close to the just-touching position because I've found the pressure jumps throw the ES out, and accuracy also showed day-to-day inconsistency. So my preference is to keep the bullet engaged with the rifling and then my adjustment increments are from 0.2mm engaged through to 0.7mm engaged in 0.1mm steps, so 6 steps, hoping to shoot some smaller groups somewhere within those settings. As noted in the previous posts the reference point from where I take these measurements is arbitrary provided I know roughly where the two end points (jam and touch) lie, and can just be the CBTO gauge readings.

On a related but different topic, what are members using for their CBTO measurements please, and how sensitive to clamping force are the measurements if using vernier calipers, ie does the contact surface on the gauge have a tendency to bite into the bullet jacket?