Fritz, I never thought the Hornet was exactly whispering to me. But it is quieter than the .223, that's for sure.
Speer lists some reduced loads for the .223 using AA XMP-5744 powder that will get the vel. down to and even below a Hornet vel. This is only my opinion, but I think you could make some reduced loads using some fast and easily combustible powders like IMR4227 and IMR4198. Some TFL'ers have had good luck using slow handgun powders like 2400 in even larger cases, so I don't see why that won't work here. Maybe they will have a load they have had success with. Be sure to work on the loads carefully and I would suggest not trying any ball powders. They are somewhat hard to combust and might lead to a detonation, which is not exactly desirable to say the least.