Incorrect. Republicans have successfully branded themselves as gun advocates, and Democrats as anti-gun. There are as many liberal gun owners as conservatives. Liberals just don't jerk off with their guns on social media.
Some brief googling doesn't support the assertion that there are as many liberal (Democratic) gun owners as their are conservative (Republican) gun owners:
But this is way too reductive. There's lots of gun ownership in the US across all political affiliations. Additionally, gun ownership is independent of someone's views on guns. I know people with liberal views on gun ownership who don't own guns and people with restrictive views on gun ownership who do own guns.