The materials to craft them aren't being made. I also have a LAW-303 BP, but have to get the other mats crafted. Main issue are lack of materials or ridiculous MU as per usual.
I had a similar issue for one of my weapon bps. I put in an order on forum for missing ingrediant and had it filled within an hour or so. Ask an ye shall recieve?
You can even make orders for a bit under MU and it'll be filled.. A lot of people are wanting to fill orders... The orders just aren't there.