I am moving into BIAB brewing. I have bought a lot of my kits of PM from NB and the local shop. Most of the time they have premade recipes with a specific grain bill. All places have a wide variety for AG and PM but very few recipes for BIAB. Is there a scaling calculation that I can apply when I see a recipe of AG that I like but will be using the BIAB method? A secondary question....it seems BIAB is geared toward 3G batches as opposed to the standard 5G batches for PM & AG. Any thoughts on why this is?