I'd like opinions on this bust please. Do you think it is a B4 or possibly something else ? Many thanks.
He's referring to this table from RIC 7: And it looks laureate, draped and cuirassed to me. So B4. Our very own @Victor_Clark has a good page to distinguish the bust types.
Usually RIC distinguishes left-facing bust types with an "l." during this period. There does appear to be some drapery under the cuirass in your example, so your coin would probably be listed as "B4 l."