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In a new twist on the idea of concealed weapons (search), a local gun maker and gun shop are debuting a new type of firearm: one that could almost fit in your wallet.

It's a two-shot weapon made from a piece of metal the height and width of a standard credit card, and about a half-inch thick. Each barrel fires seven standard steel BBs. It will retail for $100.

"This I can see being the ultimate self-defense weapon," said Mark Koscielski, owner of Koscielski's Guns and Ammo (search), the only gun shop in Minneapolis.

Koscielski and Patrick Teel, who makes the guns in suburban Blaine at his company AFT Incorporated, gave The Associated Press a preview on Tuesday, a day before they planned to officially unveil the device.

The credit card-sized shotgun is a muzzleloader, meaning it doesn't use shotgun shells. The user has to measure out some gunpowder, pour it in each barrel, drop seven BBs in each barrel, and tamp in a small wad of paper. A knob on one end serves as a safety, and two buttons set into a hole in the body are the electrical triggers. Each barrel fires with a loud pop.

Another gun salesman was skeptical of the weapon's self-defense value. Mike O'Brien, of Joe's Sporting Goods in St. Paul, wasn't familiar with the new devices, but said muzzleloading is a "slow and tedious" process.

"Us guys here would consider something like that useless," said O'Brien. "A .177 caliber BB is ballistically a joke, OK? I'm sure it could cause injury and damage, but as a self-defense weapon, no. Not to anyone familiar with firearms."

A spokesman for the Brady Center To Prevent Gun Violence (search) was also dismissive.

"It's a silly, silly idea," spokesman Peter Hamm said. "I don't know that I would want to have one of these in my pocket for my own personal safety, never mind the safety of those around me."

Guns that small have been around in various styles for a long time, and some have become curiosities and collectors items, but have failed as weapons, said O'Brien.

"It might do damage to eyes, that sort of thing. But serious damage to a 200-pound drug-crazed evildoer, no — it'd just make them mad," he said.

Teel said the main value of the new gun is that it gives the owner a chance to get away from an attacker.

"This is no more deadly than a .22," Teel said. "But the difference is you have multiple wounds, which means you'll try to get away quicker, and it will cause more pain. ... There will be more blood, which the cops will be able to see."

They said the guns are meant to be used for close-range self-defense and wouldn't be effective as offensive weapons.

"They are very effective at five to 10 feet. They're absolutely useless at 20 feet," Teel said.

The new guns don't count as firearms under federal regulations because they're muzzleloaders, Koscielski and Teel said. It's illegal to carry one in Minnesota without a permit for a concealed handgun, they said, and they both pledged not to sell them to anyone without valid identification and either a carry permit or a purchase permit.

Thirty-seven states have laws that require officials to issue concealed carry permits to qualified applicants and nine others have laws that give officials some discretion over whether someone gets a permit. Only Kansas, Illinois, Nebraska and Wisconsin lack a law allowing some form of concealed carrying of guns.

Hamm said the Brady Center isn't as concerned about the credit card-sized shotgun as it is about more powerful weapons because it's less likely to be lethal. He saluted the makers' ingenuity, but questioned whether the gun will find much of a market.

"It sounds like having a little grenade in your pocket more than anything else," he said.

Koscielski was widely credited with coining the term "Murderapolis" when the city's homicide rate shot up in the 1990s. He's run unsuccessfully for mayor, fought zoning battles to stay in business and been investigated by federal agents.

Koscielski conceded that gun opponents are likely to criticize the new devices. But he said they're legal, will set off metal detectors and are readily identifiable.

"We all have a right to defend ourselves," he said.