Male democrats are owning FEWER guns? The only reason I could see for that happening is if more male Democrats are acquiring felony convictions and have the wit to deny owning firearms.
Otherwise, I'm HIGHLY skeptical about any surveys on gun ownership - most people I know don't answer either mail or phone polls at all, and certainly won't truthfully answer questions about guns, jewelry, fur coats, or anything else about valuable items they may own.
Although several years ago someone got hold of information from the BATmen about the numbers of legally owned machine guns, SBRs, and suppressors owned in each state (hopefully only metadata, not personal information) and tried to infer overall gun ownership from the number of NFA tax stamps issued on a state by state basis.