If there's a bit of blow-by, it can sound 'extra' hollow - but can't say as I've hear a bell-ringing sound. You'd think with 85gr. 3F, you'd get a bit of a crack form a 16 bore - I'd estimate it must be doing about 1,250fps with a ball lighter than I was shooting, as long as your patch wasn't too thin.
85gr.3F used to do 1,225fps from my 14 bore rifle. It cracked.
Sub-sonic reports can sound really wierd, though.