American Tactical Imports 1911-Style FX45 "Fatboy" 45 ACP Pistol


by Jeff Quinn

photography by Jeff Quinn & Boge Quinn

August 28th, 2011


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Click pictures for a larger version.


ATI's FX-45 "Fatboy" pistol packs 13 rounds of 45 ACP into a compact weapon.





Extended magazine release.



The Fatboy uses a dual-spring guide rod system.







The Fatboy has no firing pin safety.





UpLula mag loader makes loading the Fatboy magazine much easier.





American Tactical Imports of Rochester, New York always has one of the busiest booths at SHOT Show every year, and the 2011 Show was no different. Their booth is invariably filled with interesting firearms that are a bit different from those on display throughout the show. One pistol that piqued my interest earlier this year at SHOT was the ATI Fatboy. 2011 marks the 100th Anniversary of the 1911 auto pistol; that classic design is more popular now than at any time in its history, and there are numerous variations of the 1911 pistol currently in production. This brings to mind thoughts of just how far the platform can be changed and still be a 1911. The ATI Fatboy is pushing the limits of that already. While the slide profile, along with the trigger and safety systems are pure 1911, the design of the frame, barrel, recoil spring and barrel bushing are different. In fact, there is no barrel bushing. This has been done before, quite successfully, and it is proven that such a coned barrel profile needs no bushing. Detonics did this decades ago, as have others, and it works well, returning the barrel to the same position in relation to the slide, every time.

The first thing to get most people’s attention is the wide-body grip portion of the frame. At first glance, it looks to be too wide for a good grasp for shooting, but it is thinner overall than a single-stack 1911 with grip panels. The overall width of the grip portion of the Fatboy frame is almost one-tenth of an inch thinner than a single-stack 1911 with grip panels. The Fatboy eliminates the need for grip panels at all, as the frame serves as the grip, and is textured for a secure hold on the pistol.

Almost every piece of this Fatboy is made of steel. The only exceptions are the polymer base plate on the twelve-round magazine, the spring retainer on the dual-spring recoil guide rod, and the aluminum trigger. Everything else is a matte-black finished steel.

Critical specifications for the Fatboy are listed in the chart below. The weights are listed in ounces, and linear measurements in inches. The grip and frame widths were measured at their widest points. The maximum width is measured across the grip, and includes the thumb safety. The height includes the sights and the magazine base. The trigger pull is listed as pounds of resistance. The weight includes the empty twelve-round magazine. Length is measured from the muzzle to the tip of the beavertail grip safety.

Weight 36 ounces
Height 5.5 inches
Length 6.8 inches
Slide Width 0.922 inch
Maximum Grip Width 1.2 inches
Frame Width 0.775 inch
Maximum Width 1.37 inches
Trigger Pull 6.6 pounds
Trigger Reach 2.72 inches
Barrel Length 3.22 inches
Magazine Capacity 12
Magazines Supplied 1

I tested for velocity with my chronograph set at twelve feet from the muzzle, and an air temperature of eighty-eight degrees Fahrenheit, with a sunny sky and a slight breeze and moderate humidity. Velocity readings were taken at an elevation of approximately 541 feet above sea level. Velocities are listed in the chart below, and are listed in feet-per-second (fps). FMJ is a full metal jacket bullet. JHP is a jacketed hollowpoint. DPX is an homogenous copper hollowpoint bullet. Glaser is a specialty pre-fragmented bullet inside a copper alloy jacket. PB is Pow’RBall. EPR and AF are high performance specialty bullets as loaded by Extreme Shock Ammunition. LWSC is a cast lead semi-wadcutter bullet. Velocities are listed in feet-per-second (fps). Bullet weights are listed in grains.

Ammunition Bullet Weight Velocity
Cor-Bon JHP 200 980
Cor-Bon JHP 165 1010
Cor-Bon JHP 230 880
Cor-Bon DPX 185 1008
Cor-Bon PB 165 1061
Cor-Bon Glaser 145 1122
Stryker FMJ 230 736
Buffalo Bore JHP 230 860
Buffalo Bore FMJ 230 845
Handload LSWC 200 899
Extreme Shock EPR 185 1001
Extreme Shock AF 125 1320
WCC 1911 Ball FMJ 230 703

For accuracy testing, I used a Target Shooting, Inc. handgun shooting rest, with the pistol handheld and the front of the frame resting in the V-cradle of the TSI rest. Accuracy was good, especially considering the short sight radius. The best groups fired averaged around two and one half inches, with the largest group measuring three and five-eighths inches spread for five shots at twenty-five yards. More practical to the intended use of this pistol, keeping a magazine of ammo centered on a human silhouette target at five, seven, ten, and fifteen yards was easy, aided by the thirty-six ounce heft of the Fatboy.

Functioning was very good. The trigger pull, measuring six pounds, ten ounces, is heavier than I like on a carry gun, but that is easily corrected. There were two malfunctions experienced firing this Fatboy. From the first magazine of ammo, I had one failure-to-feed. After that, everything fed, fired, and ejected perfectly. Also early on, not a malfunction, but with some loads, ejected cartridge cases would hit the shooter on the forehead. Again, this problem disappeared later. During one rapid-fire string, the slide locked back before the magazine was empty, but again, that only happened one time. After those two incidences, functioning was perfect. The Fatboy functioned very well, feeding every type of ammo listed in the velocity chart above.

The wide grip area of the Fatboy does not affect holstering, and the pistol fits into any standard 1911 holster which does not cover the grip. The grip is shorter than on a standard 1911, and hides well under a loose shirt or jacket, properly holstered. The Fatboy has a very good set of sights, with a black post in front with a white dot, and an all-black rear sight of the useful and popular Novak style, adjustable for windage correction by moving laterally in its slide dovetail.

The ATI FX45 Fatboy is a good, reliable auto pistol, having a thirteen-shot capacity, while still remaining relatively compact. It is a good choice for concealed carry, in a properly fitted holster. The Fatboy runs well on high performance hollowpoint defensive ammo, is easy to shoot, and easy to shoot well.

Check out the Fatboy and other weapons from American Tactical Imports online at

To order the Fatboy online, go to

For the location of an ATI dealer near you, click on the DEALER LOCATOR at

To order high quality 45 ACP ammunition, go to,, and

Jeff Quinn

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Click pictures for a larger version.


Author shooting the ATI Fatboy.





Fatboy (right) compared to a single-stack 1911 (left).





Twelve-shot double-stack magazine.





The Fatboy fits standard 1911 holsters.



Accuracy testing was done at 25 yards, handheld over a Target Shooting Inc. handgun rest.