HELENA - The weapons of political campaigns are well-known: rhetoric, promises, ads - sometimes dirty ones.

But rarely do those weapons include a double-action revolver.

Rarely, said Gary Marbut, president of the Montana Shooting Sports Association, does the public know if political candidates are straight shooters literally.

Marbut aims to end that. He's challenging all Montana's congressional candidates to a shooting competition.

Marbut invited Republican Sen. Conrad Burns, Democratic challenger and state Senate President Jon Tester, Republican Congressman Denny Rehberg and his opponent, Democrat and state lawmaker Monica Lindeen to compete in pin shoot, in which the candidates will shoot down bowling pins.

"The pin shoot is a fun event," Marbut said from his Missoula office. "It's something that novices can do. It's kind of fun with political overtones."

The shoot-off - contestants are timed to see how fast they can shoot over the pins - is scheduled for the Deer Creek Shooting Center near East Missoula on July 23. The cost is free for the public, Marbut said, but people must bring their own eye and ear protection.

So far, only Lindeen has expressed an interest in going.

"Monica learned to shoot with her dad," said Jayson O'Neill, a Lindeen spokesman. "She thinks it would be a blast to get out on the shooting range again."

Lindeen's opponent Rehberg won't be going, but his press spokesman, Dustin Frost, whose father is a member of the Duck Creek Shooting Center, is planning on attending.

Frost, a member of the Montana National Guard, said he hasn't decided what gun he'll compete with, but he's looking forward to it.

"Any time I go home, that's usually where we end up," he said. "This is almost like a vacation."

Neither of Montana's Senate candidates will attend.

Burns has a pre-scheduled event at Pompey's Pillar, the sandstone outcrop east of Billings in the Yellowstone River valley where William Clark scratched his initials on the return trip of the Lewis and Clark expedition.

Burns is going to commemorate the new interpretive center at the national monument, which the senator helped get the $4.9 million to build, said Sarah Pompei, a Burns spokesman.

"It sounds like a fun event and he wishes he could be there," she said.

Burns may send some of his staff members who served in wars in Iraq and Afghanistan, she said.

Tester, a Big Sandy farmer, will be taking a break from campaigning to catch up on work at the farm, said Matt McKenna, a Tester spokesman.

"Harvest is just around the corner and this is a busy time for all Montana farmers," he said.