Personal opinion. As stated, silicon oil (or any other oil) is not a good pressure lubricant. Dust and other debris tend to stick to oils as well.
Danzac® is one commercial name for Tungsten Disulfide. It is easier to apply than moly, but a bit messier. It works well, and you gain a few FPS. The question remains, why use any lube? Lead by itself is fairly slick, and not near the (overall) mess lubes are.
I will admit this. Casting your own slugs require denser alloys than those used to swage slugs, and their coefficient of friction is somewhat higher. In these cases, lubes might help reduce fouling.