Here is the "study" that they site:
They "trace" guns by if the gun was involved in any crime, even if the gun never fired. IE the gun itself was stolen, or a drug dealer busted but the gun was in the closet. That's how they got "every 48 hours"
Their shooting examples didn't happen in Maryland (closest was the DC snipers) and they used high profile crimes as examples.
It's a completely bogus study.
Written in 1993. Excerpts:
Assault Weapons: Police Data Shows BATF Traces to overestimate Criminal use by 1000%
nearly 80% of BATF gun traces do not involve guns used in violent crime; the traces are for technical violation of gun control laws, such as possession of a firearm without a license.