(CNN) -- Vice President Joe Biden, backing what he says are common-sense gun control measures, on Thursday criticized those who say the proposals are attempts to violate constitutional rights. "Tell me how it violates anyone's constitutional rights to limit (ammunition clips) to 10 rounds." Biden said at a news conference with New York Mayor Michael Bloomberg. "Think about Newtown ... . Think about how many children and teachers may be alive today had (the shooter) had to reload (more often than) he did."