Handgun design has always been a tricky business of balancing size and weight against ammunition capacity and performance. This is especially true of models intended for daily concealed carry. Just how small, yet powerful, can a handgun be? When it comes to double-action revolvers, the small-frame, five-shot .357 Magnums have been the most potent pocketables for quite a while now. Time tested models include the 25.2-oz. blued steel Ruger SP101 and the 23-oz. stainless steel J-frame Smith & Wesson 640 Pro.
But occasionally, a gunmaker will buck the subcompact, five-shot, magnum wheelgun trend by offering a model that maintains the same small frame and grip size profile while squeezing a sixth round into the cylinder. The latest model to do this is the all-stainless steel Diamondback Firearms SDR. Here is a closer look at what this new snub-gun has to offer.
The SDR is Diamondback’s first defensive revolver.
The SDR is an all-stainless steel double-action/single-action revolver with a forged frame, an exposed hammer and a swing-out cylinder. Although this gun is by no means a clone of Kimber's K6S double-action-only, six-shot .357 Mag., it's evident in the SDR's configuration and feature set that the K6S was used as a starting point for the design. Nevertheless, it's 1.8 ozs. lighter than the K6S with an unloaded weight of 21.2 ozs. Made here in the United States, the SDR is available with either a matte finish or the polished finish shown here.
Despite an all-steel construction, the SDR weighs just 21.2 ozs.
Snubbie revolvers have a well-earned reputation for sporting rudimentary fixed sights that can be a challenge to work with. The SDR ships with a set of useful low-profile sights that can be removed from the frame. The pinned metallic front sight houses a bright red/orange fiber-optic tube. The dovetailed square-notch rear sight is fitted with a pair of green fiber optics and is drift adjustable for windage.
The 2" barrel features a 45 degree crown and a full underlug that shrouds the knurled ejector rod. The six-shot cylinder rotates counter-clockwise with weight-reduction fluting styled after that of the Ruger LCR series. The chamber mouths are chamfered for easier reloading.
The five-shot Ruger SP101 (r.) and the six-shot SDR (l.) are both small-frame models.
As for the SDR cylinder's profile, I broke out a Ruger GP100 and a Ruger SP101, both chambered in .357 Mag., to compare cylinder widths. Using a pair of digital calipers to check all three, the six-shot GP100 had a diameter of 1.55", the five-shot SP101 was 1.35" and the six-shot SDR measured 1.38" at its widest point, or just 0.03" more than the SP101. In other words, the SDR's footprint falls comfortably within the pocket-sized, small-frame revolver category.
The front and rear sights are fitted with light-gathering fiber optics.
The left-side cylinder release is of the push-button variety, like those found on Kimber and Ruger revolvers. I have no qualms about working with release levers that are pushed forward (Smith & Wesson, Taurus) or pulled back (Colt). But for me, the push-button variety have proven to be the most intuitive to work with under pressure—just mash it, and you're ready to go. The SDR's serrated button is wedge shaped and larger than most, making it even easier to use. When open, the 6six-shot cylinder spun freely, and the ejector rod cycled reliably.
The push-button cylinder release is textured and generously sized.
It should be noted here that the SDR has a second cylinder release. It's located on the right side of the frame, right at the top of the front edge of the trigger guard. This spring-loaded, push-button release is installed in place of a yoke screw. With the cylinder opened, pressing and holding the right-side release allows the entire cylinder assembly to be pulled forward out of the frame.
The only other revolver I've personally worked with that had a quick-release cylinder like this one is the Taurus Tracker 692. That model ships with two cylinder assemblies, one chambered for .357 Mag./.38 Spl. +P, like the SDR, and the second cylinder chambered for 9 mm Luger. The folks at Diamondback say the SDR's quick release is intended to aid in easy cylinder removal for routine cleaning. But I can't help but think that the potential for future caliber-convertible configurations of the SDR is already in place.
The cylinder’s six closely packed chambers are chamfered for easier loading.
The fairly traditional rounded trigger guard houses a deeply curved, smooth-faced trigger. With small-framed and short-gripped revolvers like this one, the trigger pull is where the rubber really meets the road. If the double-action trigger is overly heavy or rough, it takes all the fun out of shooting them. The SDR is listed as having a "match-grade" trigger with a double-action pull of between 9 to 11.5 lbs. The trigger of the revolver I worked with weighed in at 9 lbs., 9 ozs. with a smooth, even pull from start to finish throughout the 0.80" arch of travel. Manually cocking the hammer for single-action fire shortened the trigger's arch to 0.15" that broke cleanly with 3 lbs., 2 ozs. of pressure.
The compact boot grip is comfortable to carry but only supports two fingers of the shooting hand.
The serrated hammer spur is a "just-right" length and width for easy, comfortable operation. The defensive revolver community is still debating over which is better for daily concealed carry, namely, double-action-only revolvers with concealed or bobbed hammers or the double-action/single-action models with exposed hammers. Simply stated, there are advantages to both. But if I was looking at compact revolvers for use as what I like to call trail-to-town guns, then being able to manually cock the hammer for more precise shot placements can be useful in the great outdoors.
A second cylinder release is located on the right side of the frame.
The SDR's grip frame is sized for the ever-popular and easy-to-find Smith & Wesson J-frame stocks. It arrives with a pebble-textured, finger-grooved soft black rubber "boot" stock. This is one of the most compact grips available and leaves the frame's polished base and backstrap exposed while providing a two-finger grip. When shooting from a standing position, using a two-handed grip, it can be helpful to tightly curl the little finger of the shooting hand under the stock's base for added support. But don't use this technique when shooting seated from a bench rest. Keep that little finger out of the way or you just might learn things about snub-nose revolvers, recoil and nerve endings that you probably don't want to know.
The quick-release cylinder makes for easier routine cleaning.
I continue to be impressed with how light and handy the SDR feels. It was the first thing I noticed when I picked it up for the first time at the SHOT Show Media Day at the range earlier this year, and one of the reasons I wanted to evaluate it. Being a six-shot .357, it seems like it should have a more forward-heavy feel. But instead, it balances nicely with the weight sitting straight down in the shooting hand.
MFT’s Ultralite belly band holster was a good fit for this concealed carry revolver.
The lighter weight and relatively slim profile also translated into comfortable carry. Since I didn't have an SDR-specific holster at hand, the revolver was tucked into a muti-gun fit Mission First Tactical (MFT) UltraLite Edition belly band. This band is designed with warm weather and no-belt clothing in mind but also rides comfortably with belted slacks and jeans. The primary concern with holsters made for multiple models is that, all too often, they overlap or cover the gun's grip frame in such a way as to make it difficult to form a proper shooting grip when drawing. But in this case, the MFT holster allowed the SDR to ride high enough that the grip was clear and easy to grasp. The moisture wicking, breathable fabrics used in the holster's backing and belt were a real plus as well.
The SDR was tested using .38 Spl., .38 Spl. +P and .357 Mag. loads.
At the shooting range, the SDR loaded, fired and ejected all of the ammunition tested without any cartridge-related issues or mechanical malfunctions. The sights were bright and useful, and the trigger pull was smooth and clean in both modes. The small rubber grip provided more purchase than I would have expected, even with the hotter loads of ammunition. But it's safe to say that those who plan to feed this gun a diet primarily composed of .357 Mag. cartridges would benefit from investing in a longer, three-finger grip.
Formal bench-rested five, five-shot group accuracy testing was conducted at 7 yards with a Garmin Xero C1 Pro chronograph used to measure bullet velocity for 10-shot strings. The test ammunition included a soft shooting Remington 110-grain HTP .38 Spl., a more potent 120-grain .38 Spl. +P Punch load from Federal and a full-power 125-grain .357 Mag. made by SIG Sauer. Here are the results:
The SDR concealed-carry .357 Magnum revolver represents a new endeavor for Diamondback Firearms, which is better known for its affordably priced AR platforms and the hybrid Sidekick rimfire revolver. Knowing they would be going toe-to-toe with well established defensive centerfire wheelgun makers, including Ruger, Smith & Wesson and Taurus, there were several important decisions to be made regarding its design and features. Thankfully, they made good ones.
The smallest group of 1.26” was fired using the Remington .38 Spl. load.
The SDR is arriving on the scene as a mature, ready-for-market product with well favored features included right from the factory. With suggested retail prices starting at $777, it’s less expensive than comparable competing models. And despite the ever present rumors of the defensive revolver's demise, a magnum powered pocketable six-shot like this one is still a perfectly viable option for personal protection inside and outside of the home.
Diamondback Firearms SDR Specifications
Manufacturer: Diamondback Firearms
Action Type: double-action/single-action revolver
Chambering: .357 Mag./.38 Spl. +P
Frame: forged stainless steel, polished finish
Barrel Length: 2"
Rifling: Six-Groove, 1:18.75" RH Twist
Cylinder Capacity: six-round
Sights: red fiber optic front, green fiber optic square notch rear
Trigger: double-action, 9-lb. 9-oz. pull; single-action, 3-lb. 2-oz. pull
Overall Length: 6.53"
Height: 4.44"
Width: 1.38" Cylinder
Weight: 21.2-ozs. unloaded
Accessories: owner's manual, zippered soft case, cable lock
MSRP: $821 (polished); $777 (matte)
