[obsessed1]

Forget trying to compare federal vital shok with federal power shok what matters is the individual components are what matters.
Case: All manufacturers cases are made of different thicknesses/ hardness. Occurring during the drawing process of the brass. Each case mfr will give different pressure spikes based on these differences.
Primer: each primer mfr uses a slightly different compound so they give hotter or longer ignition. Note there are std and mag which will further change ignition temp.
Powder: each powder has a unique burn rate and must be measured precisely keeping within the verified data for the cartridge and each bullet weight within that same cartridge.
Bullet: each bullet has varying length/ shape / weight. Bearing surface and jacket material is crucial info for safe loads.
Seating depth plays a role in pressure as does neck tension.
Generally speaking two type develop load manuals. Powder mfr and bullet mfr. ( it's good practice to compare 3-4 manuals for discrepancies)if you want a specific brand of bullet start with that mfr load data. Obviously hornady will not have data using a Nosler bullet and so on.
Simple way to describe it is
Choose your bullet. Then Find load data for that bullet or one that is very similar
Choose your powder and primer type based on the data found.
Start on the low end of the powder charge weight and load 3-5 rounds with each charge weight from light to heavy. Shoot those rounds looking for pressure signs and so on.