It all comes down to dedication. We have more truly dedicated than they do.
And then there's the pointlessness of marching in front of a gun shop. Why don't they go to where the crimes are being committed? Why not in front of the local gang leader/drug dealer's house? Oh, right. That might be dangerous. Much easier to blame the tool.
So I'll say it again:
"Sure, I'll support more gun laws for you, as soon as you and your supporters write the names of every family member and neighbor that belongs to a gang and has a gun hidden on this sheet of paper. Let me know when you're done and we'll hold a joint press conference to name names and start to really bring the cycle of violence to an end."