I have a lot of reading ahead (thanks
).
I was asking because I only have control over the weight of the powder load and the BHN of the bullet based on the brand. I get my bullets from Speer or xTreme. Speer is around 12BTN and xTreme 18BHN for the hard cast (15 for the Cowboy loads).
Missouri Bullets have a good page on this subject.
Using the formula from
https://www.missouribullet.com/technical.php
I can estimate the CUP linearly (I know it's not, but that's the best I think I can do).
For example, I have very little leading on my 38spl using the Speer 158gr LSWCHP, I use 3.2gr of Bullseye. I run it through the forumla in the link above and get BHN of 12.11, which is about the BHN of the Speer bullets. (the first article made me think of this).
I do have chore boy, based on other's recommendations.
I would like to understand more about gas checks.
I tried it for my 357mag subbie, same bullet at 4.5gr Bullseye, and I get leading. Now the formula says I should use 17.97 BTN, which means I should be using the xtreme 158gr LSWC that I have.
I will switch (I keep forgetting to change them out), I will report back on the results.
Update: I use to fire 25 lead rounds and 25 copper plated rounds, didn't notice the leading as bad. Now I fire only lead rounds and leave the copper plate for my Valquero Bisley 357.