***Disclaimer*** I have never reloaded and am trying to wrap my head around concepts of internal ballistics. Here, I will post my ignorant understanding and hope to learn from your experience; i.e. correct me when wrong.
Mods: if this thread belongs somewhere else please move it, I didn't know where to post this.
I'd like to explore the internal ballistics of straight cased cartridges and the effects therein of powder type, freebore, cartridge length, and seating depth. Examples could be 357 and 38 spc, or 458 lott and 458 WM.
My current understanding: Faster powders are better for straight cased rounds because as the bullet starts moving the area behind the bullet increases in volume more than it would in a necked-down small bore caliber. Longer freebore gives the bullet a running start and a pressure spike will occur once the lands are contacted. No freebore can cause excessive pressures because it takes more pressure to start moving the bullet.
Questions:
1. If a 357 was deep seated to the same COAL as a 38 and charged the same as a 38, would there be difference between the deep seated 38 and the down-loaded 357?
2. Does a lot of freebore and long throats (like weatherbys and the 458 WM) allow the bullet to expand in diameter before squeezing into the rifling and thereby decrease lead fouling OR do the escaping gases during the "jump" cause more lead fouling?