If you need some more specifics on The Obama's GFW history

for arguments, Dave Kopel has ammunition for you. Including
The answer is straightforward, in the Illinois legislature, Obama for SB 1195, which defines "assault weapons" much more broadly than the 1994 federal law. It included double-barrel and break-open shotguns in 28 gauge caliber and larger; and also banned .50 caliber rifles.

and

In the 2004 U.S. Senate campaign, Obama said he favored a national ban on concealed carry permits.