It seems to me that there should be no link between the two.
I recently said some things in favor of the NRA and the 2nd Amendment on r/atheism and got downvoted and ganged up on by a lot of people. They were opposed to the right to self defense.
I don't get how people who think that humans developed through evolution can't see how human flaws make a larger and more powerful government a bad thing. Humans would try to get more and more wealth and power over others, giving themselves completely unfair advantages over others. It's built into evolution.
edit. Most of the atheists I've met in real life have also been liberal.