In light of the recent mass killings in Colorado and Wisconsin, a California lawmaker is looking to close a loophole in an existing law that allows for quick reload on assault weapons.A California state senator introduced a bill aimed at slowing the amount of time it takes to reload assault weapons. Current law only allows for 10 bullets in a magazine, but the law does not account for a quick release button of the magazine.SB 249 written by Sen. Leland Yee (D-San Francisco) is trying to change that. Current law allows for quick release and rapid reload of semi-automatic weapons."Unfortunately a loophole exists where individuals have created a bullet button, where simply depressing a button on the gun with the tip of a bullet, the magazine can fall out and you can put another 10 magazine in there," said Adam Keigwin, Sen. Leland's chief of staff.California already has one of the nation's toughest assault weapon bans. Gun owners' groups are calling the proposed bill unconstitutional. Those opposing the bill said this won't keep rapid fire assault weapons out of the hands of criminals."The legislation is not going to affect the criminals or those with ill intent. It is going to affect the responsible gun owners seeking firearms for responsible means," said Alexander Bowman of 2nd Amendment Sports.The proposed bill would make the gun owner disassemble the magazine to reload.The bill's author said if criminals had to take time to reload their weapons those mass casualties in Colorado and Wisconsin could have be prevented."If somebody had to stop and unscrew the magazine to put another one in, opposed to right now with the use of a bullet button being able to shoot hundreds of bullets in a minute or two," said Keigwin.The bill has gained support among California lawmakers and is expected to be on the governor's desk by the end of the month.