Well, Tom, what I know about reloading (other than a muzzle loader) you can put in a nipple. My son is taking it up so I guess I'll learn something over time. What advice should I give him if he makes the dumb mistake of using apple juice or cider to see if it cleans his brass? The only thing I tell my son is to use only that which is designed to do the job, no home remedies.
There's "home remedies", and then there are "home remedies".
A case in point being RTFM's threads on WD - 40 and Ballistol .
Another "home remedy" story, years ago there was a cleaning solvent made by Dow Chemical called "Janitor in a drum".
There was an urban legend that if bald people rubbed it on their heads they would grow hair.
Scientists decided they were going to debunk this potentially dangerous rumor and started researching it.
Good by Janitor in a drum, hello Rogaine.
Turned out it worked.
The thinking in the original post seems to be that apple juice and Cider are mild acids, If it were me I would sooner use vinegar since it's a stronger acid, so it would work faster and it's less likely to leave sticky residue .
The problem would be avoided if they just dry tumbled the brass in corn cobs which is what Thompson Center used to do with their brass parts.