Make: K&B Custom.

Model: .357 Magnum Automatic

Serial Number: C2330

Year of Manufacture: Circa 1985–1990s

Caliber: .357 Magnum (WILL NOT chamber .38 Special)

Action Type: Semi-Automatic, Single Action, Fed by Detachable Magazines

Markings: The left side of the slide is marked “COONAN INC. .357 MAGNUM AUTOMATIC”. The right side of the frame is marked “K&B CUSTOM MAPLEWOOD, MN. U.S.A.” The right side of the frame is marked with the serial number “C2330”.

Barrel Length: 4”

Sights / Optics: The front sight is a blade integral to the slide. The rear sight is a square-notch sight dovetailed to the slide.

Stock Configuration & Condition: The grips are black checkered rubber panels. There are minor handling marks but no chips or cracks. The checkering is sharp. The grips rate in about Excellent overall condition.

Magazine Quantity & Condition: Five 6-round .357 Magnum stainless steel magazines, all in Fine condition.

Type of Finish: Stainless Steel

Finish Originality: Original

Bore Condition: The bore is bright, the rifling is sharp. There is no visible erosion in the bore . In this writer’s opinion, the bore rates 9/10.

Overall Condition: This pistol retains about 98% of its metal finish. The balance of the finish shows light operational wear along the barrel hood and minor handling marks on the frame and slide. There are a few faint scratches around the grip screws and takedown pin. The screw heads are sharp. The pins are clean. The markings are sharp. Overall, this pistol rates in about Excellent condition.

Mechanics: The action functions correctly. We did not fire this pistol. As with all used firearms, a thorough cleaning may be necessary to meet your maintenance requirements.

Box, Paperwork & Accessories: This pistol comes with five stainless steel 6-round magazines.

Our Assessment: The Coonan .357 Magnum Automatic was a bold engineering statement—combining the power of the .357 Magnum revolver cartridge with the familiar handling and magazine-fed reliability of a 1911-style semi-automatic pistol. Unlike standard 1911s, this design uses a pivoting trigger and redesigned internals to accommodate the high-pressure revolver round.

Manufactured in Maplewood, Minnesota by K&B Customs, these pistols were low-production, high-performance niche firearms that found a cult following among enthusiasts and collectors alike. The .357 Magnum cartridge delivers serious power in a semi-auto platform, making this pistol a standout in terms of both performance and novelty.

With five original magazines and 98% of its finish intact, this Coonan is an outstanding acquisition for collectors, 1911 aficionados, or those intrigued by unique American engineering. Don’t miss out on adding a piece of modern firearms innovation to your collection.