It was only 2024 when we first featured the Diamondback Firearms SDR in CONCEALMENT Issue 38. That polished stainless steel piece puts six rounds of powerful .357 Magnum in a package roughly the size of a five-shot .38 Special J-frame. Then, they followed up with a 9mm model chock full of ballistic surprises we detailed in Issue 46 (that one was liked so much it quickly became a carry piece).

Now Diamondback is back again, fulfilling their promise that they are dedicated to the revolver space with the new SDR-A. What you see here on the page is technically a pre-production prototype, but only technically — Diamondback doesn’t anticipate a single change between what we’re writing about and what’s going to be on the shelves by the time this issue publishes.

Diamondback Firearms SDR-A SPECS

• Caliber: .38 Special
• Capacity: 6
• Barrel Length: 2 inches
• Overall Length: 6.7 inches
• Height: 4.92 inches
• Width: 1.38 inches
• Weight (unloaded): 15.6 ounces
• MSRP: $614

WHAT’S IN A NAME?

The “A” in “SDR-A” stands for the element in the 13th place of the periodic table, aluminum. If you’re thinking that aluminum isn’t as strong as stainless steel, of course you’re right. As such, instead of being rated for .357 Magnum like its more-substantial siblings, the SDR-A is “only” rated for .38 Special +P rounds. While the frame is forged 7075-T6 aluminum, the pressure-bearing barrel and cylinder are still formed from stainless steel.

What aluminum does gift you is lighter weight and a lighter price: the Diamondback SDR-A is 5 ounces lighter and upward of $200 less than other SDRs. When it comes to concealed carry, ounces can make the difference between leaving a gun at home and putting it inside your pants. 

Our example has a nicely matte bead-blasted finish for a clean look. It’s not as flashy as the polished stainless, but it doesn’t smear up with fingerprints either.

HAMMER & TRIGGER

At least as important as the elements making up the frame is the fact that the SDR-A has no external hammer to snag on a shirt or foul a draw. As such, the Diamondback SDR-A is a double-action-only revolver. This means the trigger does several jobs during the press: The cylinder rotates to align a [ideally unfired] cartridge between the firing pin and barrel. 

Simultaneously, the mainspring compresses, storing up energy. Finally, when the hammer is fully cocked and ready, the trigger releases it like a mousetrap — the primer is struck, the gunpowder ignites and explodes, and the projectile flies through the barrel. 

A single-action-only revolver is an older, less sophisticated design, where the hammer must be manually cocked for each shot. The cylinder still rotates and the mainspring still compresses, but a person must first manipulate the hammer then the trigger rather than just the trigger itself. 

A DA/SA revolver can go both ways, like the other Diamondback SDRs we’ve covered. 

The double-action pull is heavier and longer (because it’s doing more work), but a correspondingly lighter and shorter pull is accessible by cocking the hammer yourself —though one may not always have the opportunity outside a controlled environment. 

Because the trigger on the SDR-A is not bobbed (an otherwise normal revolver that had a mohel go a bit too far) but instead has its hammer fully concealed and encased, the trigger pull itself matters more than most. 

You’re not going to be able to tab it back for a light single-action pull, but thankfully we’re still essentially talking about the same SDR Diamondback Firearms has already been putting out for years now — they’ve always described the trigger as match grade, and we’ve called it indulgent. In double-action it doesn’t stack, ever-increasing in weight until the break, but instead you hit a wall (of sorts) prior to a predictable release. (The official specification for trigger weight is 9 to 11.5 pounds; if you’ve ever shot an excellent Smith & Wesson, this is like that.) 

It’s not exactly like shooting single-action, but, with practice, it’s well more than usable — and the double-action is damned good anyway.   

GET A GRIP

The Diamondback SDR-A is compatible with most J-frame grips right out of the box, so the aftermarket is wide open. For their part, Diamondback changed the design of their custom overmolded Hogue grip a bit, opting for one just a little longer. It allows more shooting hand purchase, helpful for those with size XL mitts. 

SIGHTS & OPTICS

Like its predecessors, the SDR-A features a green fiber-optic rear sight paired with a red front. The rear sight is a Glock-pattern dovetail, but we’ve never messed around with replacing it. It wouldn’t hurt to see a truly excellent night sight as an option like the Trijicon HD XR, but as we’ve said from the beginning, a factory dot mount is what we want. 

At the time of writing there still isn’t a mount for a micro-dot, and while we’ve threatened to drill and tap our own (we’ve done this with more than one revolver in the past), Diamondback asked us to “please wait a little longer.” We’ll take that on faith that there will be more on that front — they’ve come through with their other promises, after all. Besides, the top of the 7075 frame doesn’t have a whole ton of meat, and any tapped holes are bound to gall out. There was some consideration as to whether a Glock dovetail plate could be used, but it would have to be a custom job because the frame gets in the way. And so, we wait.  

LOOSE ROUNDS

Revolvers are a space that’s been neglected by many modern companies, largely because they’re damned hard to do, at least to do right — double-so if you want to do something new. 

The impression of simplicity is deceptive and only exists in the aesthetics, because the actual internal mechanics are hidden behind rarely removed plates and the nightmares about timing and lockup tolerances are largely burdens of gunsmiths and engineers. It’s no wonder most companies just stay out and make yet-another-P365 or gee-look-a-Glock.

In our very first article on the SDR we mentioned that it was practically begging for a bobbed or concealed hammer model, and now Diamondback has options for both.

Diamondback Firearms keeps pushing themselves further into this space   — hot damn, we’re here for it. 

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