The thinner the carrier oil, the harder it becomes to hold the active ingredient in stable solution. While castor oil can support concentrations up to 30 mg/mL, the question remains: is that truly necessary? For a compound like Proviron, where relatively small doses are sufficient to achieve noticeable androgenic and anti-estrogenic effects, chasing ultra-high concentrations may be excessive.
15mg seems to be the best balance between solvent needed and dosage. At this level, castor oil with 28–35% benzyl benzoate is more than sufficient for stable formulation. mct you need much higher BB. I believe his dosage seems plenty and smart for the long term use people would use proviron for.
Pursuing maximum concentration as a badge of brewing competence often backfires... elevated solvent levels compromise tissue compatibility and increase the risk of injection-site reactions. High BB percentages (>40%) can cause irritation, and solutions may crash when ambient temperatures fall, leading to visible crystallization and compromised bioavailability.
Its trade-off really
A moderate concentration executed cleanly will always outperform an unstable high-strength brew in both efficacy and safety.