If the NRA's claim that guns help reduce crime were true, the U.S. would have the lowest homicide rate among industrialized nations instead of the highest one.
Of all 50 states, Mississippi came in last for weakening gun legislation this year.
The scorecard each year consistently shows the states with better grades have a lower rate of of gun deaths.
The measure marks a rare effort by a leading Republican lawmaker to curb gun purchases.
Hostage-taker Monis was not on any security watchlist despite being well known to Australian authorities
Anti-gun advocates are calling for greater efforts to trace stolen weapons following the deadly siege in Sydney