In both cases, people who find an “ick” factor in something (be it guns or gay marriage) are against it. Those who fit in the group (either owning a gun or being gay) feel it is a personal matter others should get out of.
In both cases, people post to disputed statistics for the harm caused by the parties they wish to regulate or deny. In both cases, those opposing regulation point to contrary statistics showing how good either guns or gay marriage really are and how they are essential constitutional rights.
In both cases early civil rights issues are invoked (a number of early civil rights figures claimed that Winchester was the surest source of equality; many gay rights supporters claim the mantle of the civil rights movement).
The more I look at them, the more I see a likeness to those who wish to take away the guns others own and those who wish to ban various forms of marriage others wish to participate in.
The lone exception is that I see few gun proponents claiming that gun ownership will lead to a deconstruction of familiar social institutions and norms. Some proponents of gay marriage claim that with gay marriage such a deconstruction is inevitable.
What similarities and what differences do you see?