On my CA36, that pin has a head screwed on so you can't simply knock it out with a hammer. Should be the end that is sticking out the most, right side on mine. It'll release the whole magwell.
"Hey I'm the first one to say its a great country but its a straaaaange culture. This is a place where gun store owners are given a list of stolen credit cards but not a list of CRIMINALS and MANIACS. And now they're thinking of banning toy guns...AND THEY'RE GONNA KEEP THE F**KING REAL ONES!"
-George Carlin 1937 - 2008 (RIP buddy)