OzFclass

John that is a very valuable input. David.

Has anyone done any weight or other testing on HBC's lately? A mate did a recent random sample of 50 with a weight test on a high quality scale, and all were within a tenth of a grain, which is reassuring. He also took some interesting microscope pics of the Berger, Sierra and HBC. It was noticeable how good the tip and overall finish was on the Sierra 2156 and HBC, but quite different on Berger. Nothing to form a definitive conclusion on.

I have a question about the differences in base to Ogive measurements in the 155.5 pills of different batches. I have measured 55 thou difference, in this instance in the new batch the base to ogive is longer. How will this affect things as I have found a pet load and jump using the older batch? Does this mean with the new batch the projectiles will be seated further down in the case if I keep the same jump, and this will obviously effect pressures? Should I start to test further with lower powder loads to gain the same pressures as I want to keep the same jump?

Phill

Phill,
You will probably find that the overall length will vary much the same. ie 55 thou. This generally means that the ogive is the same length ( and shape ) from transition point to tip -- which in turn means that they will seat the same. ( with the same die setting ) The extra 55 thou being base to ogive ( as you have established ) is therefore within the case --reducing available case capacity, probably increasing pressure and maybe speed due to the increased bearing length of projectile.

Run Peter Smiths case dimension program to see what seating 55 thou further into the case will do..........