Modern Hoppe's #9 is mostly kerosene and petroleum distillates.
For the question asked, it is perfectly suited to the task. It is relatively benign when exposed to it topically.
The pre-1973'ish #9 had Nitrobenene in it, which was fabulous for dissolving corrosive primer residues. It smelled very different, but was also a very dangerous chemical mixture.
I recommend using an ammonia based product for removing the corrosive salts left behind by old ammunition.
Another product still in use, but not the same as previously formulated is the brown bottle "Lysol". It no longer contains the Phenolic compounds also linked to serious health concerns.
You might recall it's "mediciney" smell from your youth. Not there now.
The other product gone from our lives is Carbon-tet (CCl4) the most fabuluous organic solvent there ever was. Commonly used as a stain remover and drycleaning agent, it's a powerful carcinogen.
But please, don't ever dupe yourself into thinking an old bottle of Hoppe's #9 is safe to get on your skin. It's not. The graveyards around Midland, MI can testify to that for you. Benzene production was a local industry for almost a century.
