The National Rifle Association is the main arm of the gun rights lobby in America. So for Democrats who support stricter gun laws, a bad grade from the NRA is a badge of honor. But the Democrats at Tuesday night's debate actually have a mixed record when it comes to guns — and their varied grades show as much.

Here are the candidates' most recent NRA grades, based on the last election they ran in:

Hillary Clinton: F

Bernie Sanders: D-minus

Martin O'Malley: F

Lincoln Chafee: F

Jim Webb: A

What's interesting in these rankings is that most of the Democrats on stage are actually more liberal on guns, based on the NRA's scores, than the self-described "democratic socialist" onstage. As I previously explained, that reflects Sanders's roots in a largely rural state, which has a strong gun culture. So when guns come up, Sanders sounds less like the idealist he's loved as and more like the pragmatist his state's electorate pushes him to be.

Watch: America's biggest gun problem is rarely discussed