As evidence, he pointed to statements in gun magazines by gun industry leaders.
But then again, the logical link between gun ownership and the sales of gun magazines can hardly be called tenuous.
I pretended not to notice the gun magazines piled on a nearby counter.
An assault weapons ban and a measure to limit the size of gun magazines also passed the committee.
He cited a provision that bans sales of gun magazines that can hold more than 15 rounds.
In another sign of the growing focus on gun magazines, Colorado's House of Representatives on Monday narrowly passed a measure that would limit magazines to 15 rounds.
Mr Duggan obtained state- and county-level sales data from one of America's largest gun magazines, betting that sales would be strongly correlated with gun ownership.
The new laws broaden an existing ban on assault weapons and reduce the permissible size of gun magazines to 7 rounds, from 10.
Gun magazines that hold more than 10 rounds were banned under the federal assault weapons ban until the statute expired at the end of 2004.
