All it takes is about 100,000 signatures in 1 state to propose a bill and have the state vote on it! Then the state legislation can propose it to be an amendment! If 2/3s of the states pass the bill it will become an amendment of the constitution.
We need to be the ones to get a gun control amendment passed requiring very specific requirements. Like
a) A licence
b) mandatory mental health check every 3 months.
c) Back ground checks every 6 months
d) To register to a computer based list
e) Hold gun sellers criminally responsible if they fail to follow procedures and it results in a shooting.
f) restricting the number of bullets
g) banning military style weapons
h) limit the number of guns someone can own