The group will protest at the government's ban on private ownership of handguns.
But the Snowdrop campaign, which called for a ban on all handguns in the wake of the Dunblane massacre, has dropped its plan to field a candidate in Mr Forsyth's highly marginal seat because Labour was backing its demands.
The latest threat to Mr Forsyth's majority of just 703 comes from the Shooters' Rights Association, a lobbying group for licensing and other legislative issues, which claims 6,000 members.
Secretary Richard Law said the candidate could be his Glasgow-born wife Elizabeth, but this had yet to be decided.
He said: "The Government has gone too far. They are scapegoating decent people for police ineptitude."
The problem lay not in guns but in the licensing of them - Dunblane happened because of failures in this respect by Central Scotland police, he said. "I would have thought there was scope for a charge of manslaughter against Central Scotland Police, in the way that people in the ferry company were charged after the Herald of Free Enterprise disaster."Reuse content