i posted this thread on another forum and got no response so I hope some of the shooters and readers on this forum have some idea of what I am looking for.
I am a believer in the idea that bore lubrication with cast & lubed bullets occurrs best when the pressure of the load in great enough to cause the bullet to obturate in the bore which then forces the lube in the grease grooves under pressure onto the bore.
If this is true it may be the reason some cast bullet loads with hard cast bullets will sometimes cause leading in the bore, especially when the bullets are too hard and the load light.
What I am looking for may not exist. I would like to see a chart that would list cast bullets by hardness and the pressure required to cause the bullet obtruate enough to force the bullet lube out of the grease grooves and onto the bore.
I know Lee has a chart that indicates the pressure levels of many loads but the maximum is a pressure not to be exceeded. The chart doesn't appear to indicate the pressure at which a bullet of a given hardness will begin to obturate. Also those maximum loads are not good for accuracy in fact they are terrible.
My own experience with my cast bullets and purchased cast bullets of varing degrees of hardness has had mixed results when it comes to bore leading. I have had more leading with hard cast than the softer or medium hard bullets when using mild level loads. This suggests the harder boolets are not under enough pressure to obtruate and help with the lubrication.
Most of my handgun loads are lower to midrange velocity, 1100 to 1500 fps. My rifle loads run from around 1200 to 1700 fps. I don't do any long range shooting and don't push my handguns to the limit. I simply enjoy shooting for pleasure and reloading.
I guess the bottom line for my question may be, "Is there a direct link between bullet hardness and the pressure level of the load when bore lead or not is the issue."