I disagree, and here’s why.
Lead bullets have lower engraving force then copper jacketed bullets. Peak pressure is usually realized as the bullet is being engraved with the rifling.
This is represented in software like QuickLOAD as an offset. Once the bullet is engraved and begins to travel down the bore pressure drops precipitously. The small amount of gas the blows by a jacketed or lead bullet, has little affect on overall pressure as the volume behind the bullet is rapidly expanding dropping the pressure faster then the blow by.
When developing loads for a ballistics manual a max load is worked up based on SAAMI MAP. From there ~10% reduction is taken to generate a start load. So if the max load has more powder then the start load would also have more powder.
For a given bullet weight, a cast bullet will allow more powder to be place behind it then a jacketed bullet before it hits SAAMI MAP. Thus it’s max and starting loads will be higher then a Jacketed bullet.
I’m a faceless nameless guy on the internet. So take it with a grain of salt and do what you feel is best for your firearms and loads. Using a start charge for a Jacketed bullet for a cast billed of the same weight, when cast load data is unavailable, is pretty common.
Reloading...it’s like knitting for men.