I read on another forum that there is a formula for figuring out the powder charge between 2 bullets using the same powder, design, shape and depth but different weights.
For example, if I had a 115g rn and I knew my confirmed recipe called for 5g of powder, if I then went to a 147g but did not have a recipe for it, I could use the following equation for a starting point (minus a few percent of course):
Square root of (larger bullet weight divided by smaller bullet weight)
For lighter bullets, you would multiply that number by the original charge and for heavier bullets, you would divide it
So if I was working with 115g RN using 5g of powder and I wanted to find the right powder charge for the same bullet at the same depth with a weight of 147g the equation would be:
147/115=1.278. The sq. root of 1.278=1.13
the proper charge for the 147g bullet would be 5/1.13=4.42g
or if the 147 was 5g and I was looking for the 115:
147/115=1.278. The sq. root of 1.278=1.13
the proper charge for the 115g bullet would be 5x1.13=5.65g
Has anyone used this? Is it terrible advice or is it a safe equation?
For example, if I had a 115g rn and I knew my confirmed recipe called for 5g of powder, if I then went to a 147g but did not have a recipe for it, I could use the following equation for a starting point (minus a few percent of course):
Square root of (larger bullet weight divided by smaller bullet weight)
For lighter bullets, you would multiply that number by the original charge and for heavier bullets, you would divide it
So if I was working with 115g RN using 5g of powder and I wanted to find the right powder charge for the same bullet at the same depth with a weight of 147g the equation would be:
147/115=1.278. The sq. root of 1.278=1.13
the proper charge for the 147g bullet would be 5/1.13=4.42g
or if the 147 was 5g and I was looking for the 115:
147/115=1.278. The sq. root of 1.278=1.13
the proper charge for the 115g bullet would be 5x1.13=5.65g
Has anyone used this? Is it terrible advice or is it a safe equation?
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