Diamondback’s DB FS Nine, the company’s first attempt at a full-size semi-automatic, is a polymer-frame striker-fired 9 mm with a 4.75" chrome moly barrel and an unloaded weight of 21.5 ozs. That’s roughly two-and-a-half times as much as the company’s demure DB380 weighs, so the FS Nine represents a step up in size for Diamondback as well as a leap into the crowded field of striker-fired autoloaders.
The FS Nine features a Melonite-treated stainless steel slide with bold serrations at the front and rear and a set of white three-dot fixed sights. The rear sight is dovetailed into the slide, while the front sight is machined into the steel slide. A cocking indicator protrudes from the rear of the slide, and a narrow port on the top side of the chamber allows for visual inspection. There is no traditional external manual safety but the FS Nine does have both a trigger safety and a firing pin block safety. The grip is very large and has a unique contour, wide at the bottom and narrowing at the top so that the hand slides firmly into position for a high, consistent hold on the gun, and the entire grip surface is treated with Diamondback’s unique and functional snakeskin-style texturing. The double-stack magazine holds 15 rounds, and the magazine well has a cavernous opening that makes reloads quick and easy. A MIL-STD1913 Picatinny rail on the front of the polymer frame securely accommodates lights or lasers. The controls are minimal; a small slide stop is found on the left side of the gun, and takedown is very similar to Glock pistols, from which the FS Nine borrows some styling cues. 
The first impression of the FS Nine is that it is large. It’s not heavy, not ponderous or bulky, but it’s a big polymer semi-automatic. The distinctively styled grip is comfortable, and shooters with large hands will appreciate the added space. The flared magazine well and finger extension on the magazine provided a secure platform to hold the gun while firing from the bench. The fixed sights are large and easy to see, but they are better equipped for close-range target work than bench shooting. The machined front sight is relatively narrow, and this creates a visible gap between the exterior of the front sight and the interior of the rear sight when aiming. The trigger was good, breaking at slightly more than 5 lbs., 8 ozs., although there was considerable take-up and it wasn’t particularly smooth. The trigger does, however, have a short reset, and from the bench it was easy to fire a shot, release a bit of pressure to reset the trigger, and then fire again.
For this test, we used Federal’s HST 124-gr. jacketed hollow points, SIG Sauer Elite 124-gr. JHP, and Hornady’s Critical Duty FlexLock 135-gr. ammunition, and tested the FS Nine by firing five consecutive, five-shot groups at 25 yds. from a fixed rest. Accuracy was respectable, and group sizes ranged from 1.70" to 3.88" with averages hovering around 3". The SIG Sauer Elite ammunition was the most accurate load tested, averaging 2.62", while the Federal load performed almost as well with groups averaging 2.81". Hornady’s Critical Duty ammunition averaged 3.12". The FS Nine performed without any feeding or ejection problems throughout the 75-round test, and after testing on the bench we ran through a course of fire standing as well as moving. We liked the overall balance of the FS Nine, especially with a full magazine, and even though it is a bit large for concealed carry it is just right for target shooting and home defense thanks to its long sight radius and enough weight to mitigate recoil. The texture on the grip is both cool and functional, and the tapered grip channels the hand into the proper position, though after a few dozen rounds of defensive ammo we wished the top of the grip had been wider to lessen the bite of recoil.
For Diamondback Firearms, the FS Nine is a logical step into the large and lucrative full-size semi-automatic segment. It has a long list of features that allow it to compete with other, similar-size semi-automatics, and yet it carries a suggested retail price of $483, which is significantly less than many of the current class leaders. We wish that the sights were a bit better and were adjustable, and the trigger is functional but could be cleaned up. For the price range, though, the FS Nine is competitive and likely to expand Diamondback’s following.
Diamondback DB FS Nine
Manufacturer: Diamondback Firearms, 4135 Pine Tree Place, Cocoa, FL, 32926; (877) 997-6774; diamondbackfirearms.com
Cartridge: 9 mm Luger
Action Type: double-action, striker-fired center-fire pistol
Frame: polymer
Barrel: 4.75" chrome moly
Rifling: six-groove, 1:10" RH twist
Magazine: 15-round detachable box
Sights: machined front post, dovetailed square rear, fixed
Trigger: single-stage, 5-lb., 9-oz. pull
Overall Length: 7.8"
Width: 1"
Height: 5.6"
Weight: 21.5 ozs.
Accessories: owner’s manual
Suggested retail Price: $483
