Post by Bullshop on Sept 16, 2022 18:28:00 GMT -7
The two most often asked questions I get are about bullet alloy hardness and how it relates to chamber pressures and how it relates to bullet expansion on impact. There are a couple very simple very basic rules to go by to be in the center of the ball park on those two points. Those are,
as to the correct alloy hardness for chamber pressure/velocity, ------ 1 Brinell point per 100 fps This is a very simple rule that is based on average chamber pressure for velocity. There is obviously going to be a lot of overlap but as I said your going to be near the middle of the ball park of overlap. I use velocity but its really pressure that is important but using velocity keeps it very simple I say average pressure for velocity because actual pressure can be vastly different between a very slow powder and very fast powder at an equal velocity with equal bullet weight. This is the reason I always suggest having a load data manual that also lists pressure with velocity. In selecting a powder to work up a load I always go for the powder that give the lowest pressure while still giving the desired velocity. This is true for any type of bullet but especially true when trying to push cast rifle bullets to high velocity with good accuracy.
as to alloy hardness for bullet expansion --------- Brinell # x 100 equal impact velocity . Again there is a lot of overlap much due to the inconsistency of impact media such as bone, muscle, soft tissue etc but again using this simple formula you will be safely near the center of the goal post with room to spare on either side.
I know I have posted this before somewhere but for the sake of the new kids at school its no problem to do it again.
Maybe some of my customers by this will be able to see what a near impossibly tall order they request when wanting a bullet that will handle 2700 fps velocity and still expand on a deer at 400 yards.
as to the correct alloy hardness for chamber pressure/velocity, ------ 1 Brinell point per 100 fps This is a very simple rule that is based on average chamber pressure for velocity. There is obviously going to be a lot of overlap but as I said your going to be near the middle of the ball park of overlap. I use velocity but its really pressure that is important but using velocity keeps it very simple I say average pressure for velocity because actual pressure can be vastly different between a very slow powder and very fast powder at an equal velocity with equal bullet weight. This is the reason I always suggest having a load data manual that also lists pressure with velocity. In selecting a powder to work up a load I always go for the powder that give the lowest pressure while still giving the desired velocity. This is true for any type of bullet but especially true when trying to push cast rifle bullets to high velocity with good accuracy.
as to alloy hardness for bullet expansion --------- Brinell # x 100 equal impact velocity . Again there is a lot of overlap much due to the inconsistency of impact media such as bone, muscle, soft tissue etc but again using this simple formula you will be safely near the center of the goal post with room to spare on either side.
I know I have posted this before somewhere but for the sake of the new kids at school its no problem to do it again.
Maybe some of my customers by this will be able to see what a near impossibly tall order they request when wanting a bullet that will handle 2700 fps velocity and still expand on a deer at 400 yards.
