Yeah, I had actually started typing in a paragraph preceding the one you've quoted about "[mis]identifying military ordnance," but I think that it refers to explosives, at least in large part.
Also, note that:
Analysis of source location trace data for specific market area, when adjusted for time-to-crime, may not only reveal actional investigative leads, but also that secondary sources (e.g., gun shows, thefts and private sales) are a greater source of trafficked crime guns than licensed dealers.
This tells me that somebody
already suspected that FFLs weren't the real problem. I'm also bothered by the "gun shows" reference. Gun shows are nothing more than a collection of FFLs and private individuals, buying and selling. It's not like the gun show itself has anything for sale.