American Tactical Imports 45 ACP Lightweight Fatboy Semi-Automatic Pistol

by Jeff Quinn

photography by Jeff Quinn & Boge Quinn

April 27th, 2013

Click pictures for a larger version.







Ambidextrous thumb safety.





Magazine release (top), slide lock (bottom).



Very good set of steel sights.







About eighteen months ago, we reviewed the compact all-steel ATI Fatboy here on The Fatboy was a dandy little 1911 wide-body mag handgun that was built for concealed carry. To me, it had only two shortcomings; one was that it had no ambidextrous safety, and the other was that it was a heavy little chunk of a pistol. Now, ATI has corrected those two items, as the new Lightweight Fatboy has an ambidextrous safety, and as the “Lightweight” name implies, the Fatboy has lost some weight. The new LW Fatboy weighs almost nine ounces less than the original steel-framed Fatboy, which makes a lot of difference on a gun that is built for concealed carry. Like the original, the Fatboy is chambered for the 45 ACP cartridge, and packing either eleven or thirteen shots fully-loaded, depending upon the magazine that is shipped with the pistol, the Fatboy is an excellent fighting handgun. Depending upon your state and local ordinances, you can buy the Fatboy with either a ten-shot or a twelve-shot magazine. I also tried a Para fourteen-shot magazine, and it worked well. Like other pistols that are based upon the 1911 design, the Fatboy is intended to be carried with a round in the chamber, and the safety on. The Fatboy also incorporates an automatic grip safety. Thankfully, there is no magazine safety. The hammer is of the Rowell type, commonly referred to as a Commander-style hammer. The grip safety is an excellent upswept beavertail unit. The black checkered plastic grips are thin, and feel great to my hand; much better than the original grip of the steel Fatboy. The LW Fatboy uses an aluminum frame to reduce weight, but the slide, barrel, and small parts are a matte-black finished steel, with the area of barrel over the chamber polished to a natural finish. Like the original Fatboy, the barrel and slide use no barrel bushing. The guide rod is a captured multiple-spring design. The trigger is steel, as is the mainspring housing. The only plastic parts on this weapon are the grip panels, the magazine base plate, and the magazine follower. The sights are very rugged, and easy to see. Both front and back are dovetailed into the slide, and are adjustable for windage correction. The front sight has an inset white bead.

Critical specifications for the Lightweight Fatboy, as well as the specs from the original steel-framed 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 on the original Fatboy, and is measured across the ambidextrous thumb safety levers on the Lightweight Fatboy. The height includes the sights and the magazine base. The trigger pull is listed as pounds of resistance. The weight includes the empty magazine. Length is measured from the muzzle to the tip of the beavertail grip safety.
Caliber 45 ACP 45 ACP
Weight 36 oz. 27.7 oz.
Height 5.5" 5.5"
Length 6.8" 6.8"
Slide Width 0.922" 0.922"
Maximum Grip Width 1.2" 1.23"
Frame Width 0.775" 0.775"
Maximum Width 1.37" 1.43"
Trigger Pull 6.6 lbs. 6.5 lbs.
Trigger Reach 2.72" 2.72"
Barrel Length 3.22" 3.22"
Magazine Capacity 10 or 12 10 or 12
Magazines Supplied 1 1
MSRP (as of April 27, 2013) Discontinued $699.95

I tested for velocity with my chronograph set at ten feet from the muzzle, with an air temperature of seventy-two degrees Fahrenheit and a relative humidity of fifty-one percent. 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 and Tac-XP use a Barnes homogenous copper hollowpoint bullet. PB is Pow’RBall. LWSC is a cast lead semi-wadcutter bullet. HC is a hard-cast lead flat-nosed bullet.  LRSP is Buffalo Bore Low-Recoil Standard pressure ammunition. Velocities are listed in feet-per-second (fps). Bullet weights are listed in grains.

Ammunition Bullet Weight Velocity
Buffalo Bore JHP +P 230 922
Buffalo Bore FMJ +P 230 950
Buffalo Bore Tac-XP +P 185 1092
Buffalo Bore HC +P 255 933
Buffalo Bore JHP +P 185 1081
Buffalo Bore LRSP FMJ 185 733
Buffalo Bore LRSP Tac-XP 160 931
Cor-Bon JHP +P 200 1027
Cor-Bon JHP +P 230 870
Cor-Bon DPX  +P 185 1040
Cor-Bon  PB +P 165 1144
Stryker FMJ 230 823
Atomic JHP  +P 230 897
Atomic JHP  +P 185 1005
Remington FMJ 230 755
Remington JHP 230 825
NPA Frangible 140 1129
Handload  LWSC 200 972
WCC 1911 Ball FMJ 230 740

Velocities were pretty respectable from the short barrel of the Lightweight Fatboy. Recoil was very manageable. For an effective load with low recoil, I like the 160 grain Buffalo Bore load. The hollowpoint bullet expands at low velocity, and follow-up shots are very quickly managed. At about six and one-half pounds, the trigger pull is a bit heavier than I prefer, but is very crisp, and does not feel as heavy as it measures. Accuracy was very good. I did no bench shooting of this pistol, as it is made for social work, so I fired at targets from seven out to one-hundred yards, and hits were easy, due to the pistols excellent sights and handling qualities. Keeping all shots in the kill zone of a standard human silhouette target was very easy at twenty-five yards, and ringing the one hundred yard steel was pretty reliable, when taking careful aim. Functioning was flawless with every type of ammunition listed above. Every round fed, fired, and ejected perfectly. The Lightweight Fatboy is now what the original Fatboy should have been. It is a high-quality, lightweight, ambidextrous, wide body 45 ACP that is purpose-built to be an effective fighting pistol for concealed carry.

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.



Pistol comes with one magazine, cable lock, and instructions.





Ten-shot steel magazine.