Home » Rifle Scopes » Vortex Optics Diamondback 4-12x40 Second Focal Plane Rifle Scope - Dead-Hold BDC Reticle (MOA)

Vortex Optics Diamondback 4-12x40 Second Focal Plane Rifle Scope - Dead-Hold BDC Reticle (MOA)

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Vortex Diamondback 4-12x40 Rifle Scope
Image Credit - Vortex Optics

Magnification: 4-12X
Power Variability: Variable
Objective Diameter: 40 mm
Length/Weight/Tube Diameter: 12"/14.6 oz/1"
Field of View: 32.4-11.3 feet/100 yards
Eye Relief/Exit Pupil: 3.1"/10-3.3 mm
Reticle: BDC
Adjustment Info: 1/4" MOA/Click
Optics Coatings: Fully multi-coated
Finish: Black/Matte
Waterproof/Shockproof: Yes/Yes
Parallax Setting: Factory-set 100 yards
Airgun rated: No
Illuminated Reticle: No
Mounting Rings Included: No

Best Uses: Big Game Hunting, Varmint Hunting, Small Game Hunting, Target Shooting

Vortex Optics Diamondback 4-12X40 Scope Review

Close up of Vortex 4-12x40 Rifle Scope
Image Credit - Vortex Optics

Who doesn't love Vortex scope? We are certainly Vortex fans for all the right reasons. They're affordable, high quality optics that often can't be beat. Plus, they're practically indestructible, and they come with the most competitive and unbeatable customer service and warranty in the market - hands down!

The Diamondback rifle scope is no exception to the rule when it comes to all the right reasons why we recommend this baby to be mounted on your gun. It might not have all the bells and whistles that you'd expect out of a several hundred dollar scope, but it's got all the right qualities for a solid performer that's listed way below its price range.

It has fully multi-coated optics for that perfectly-clear and anti-reflective image quality that you expect from Vortex. With a single-piece tube body, you've got durability, strength, and weatherproof-ability on your side every time you head out. Don't forget that argon gas keeps your scope fully fogproof protecting your image quality and internal components.

With a fast-focus eyepiece and the precision glide erector system, you have a smooth, instant, and flawless visionary experience even under the harshest conditions.

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Checking in with the masses, they say they love the well-built construction, clear glass, and it holds its zero no matter what. However, there have been very few complaints about random defects here and there. Checking back with Vortex, they take care of the issue immediately, and of course they would since they have the best VIP warranty there is to date!


  • Price
  • Fully multi-coated optics
  • Fully weatherproof
  • Fast focus eyepiece
  • Precision glide erector system


  • Random quality control issues

Vortex Diamondback 4-12X40 Q&A:

What is the Precision-Glide Erector System?

This system consists of specially designed components in the zoom system that ensures for a smooth and hassle-free transition during magnification changes under the harshest conditions.

Does the Diamondback have Parallax Correction?

This particular model doesn't have parallax correction. Parallax is factory-set at 100 yards. However, the Diamondback 4-12X40 with AO does have an adjustable objective to customize yardages to adjust for parallax.

Is this a Heavy Rifle Scope?

The Diamondback rifle scope weighs in at 14.6 oz which is a nice weight for a 4-12X scope. Keeping it lightweight and durable is thanks to its aircraft grade aluminum construction. It's relatively compact in size measuring a full 12 inches from objective bell to the eyepiece.

What is the Dead-Hold BDC Reticle?

BDC Reticle (MOA)
Image Credit - Vortex Optics

This Diamondback rifle scope can come with either the V-Plex or the Dead-Hold BDC reticle. The V-Plex is your simple, all-purpose hunting reticle suitable for many applications. The Dead-Hold BDC reticle features stadia lines along the crosshairs for holdovers at specific yardages and windrift compensation. You can use Vortex's Long Range Ballistics Calculator (LRBC) program to find what bullet drops would be specific to your particular setup.

Differences between Diamondback and Diamondback HP Scopes?

The Diamondback line has seven rifle scope models to offer that all feature argon purged scopes with full weatherproof integrity, fully multi-coated optics, fast focus eyepiece, and the precision-glide erector system.

The High Performance (HP) line offers the same, but they also sport parallax correction, 20 MOA more in adjustments, XD glass, and XR fully multi-coated optics. The HP line currently has three models in its line. They also come with an included 4" sunshade in the box.

What are the Seven Models in the Diamondback Rifle Scope line?

This is the highest power rifle scope in the line, the 4-12X40 model. There is also the same model with the AO feature. The remaining models are the 3.5-10X50, 3-9X40, 2-7X35, 2-7X35 Rimfire, and 1.75-5X32 scopes.

What is the VIP Warranty?

It's not what you think. VIP stands for Very Important Promise that Vortex makes to you, the consumer. If you have a defective or damaged scope, they will repair or replace it at no charge to you. It's an unlimited lifetime warranty that's transferable to the current owner. You won't ever need to hang onto your proof of purchase, and you don't need to fill out any warranty or registration forms. It's simple. If you have a Vortex scope, you're covered!

Is the Diamondback 4-12X40 a SFP or FFP scope?

This rifle scope is a Second Focal Plane (SFP) rifle scope. This means the reticle stays the same size throughout magnification changes. To use the ballistic holdover reticle, you have to have the scope in max magnification for accurate yardages to apply. For more on SFP and FFP reticles, check out our "Reticle Subtension Explained" article for a clearer understanding.

Noteworthy Features:

  • Dead-Hold BDC reticle for bullet drop
  • Wind drift correction stadia lines on crosshair
  • Precision-Glide Erector System
  • Lightweight & compact for 4-12X
  • Fast focus eyepiece for easy reticle focusing

Our Verdict on Vortex's Diamondback 4-12x40 Rifle Scope

Vortex Diamondback Scope Side on
Image Credit - Vortex Optics

According to the bull's-eye, the Vortex Diamondback 4-12X40 rifle scope is preferred for one reason: it's a high-performing optic that's "nothing short of absolute perfection." If you want an excellent scope for the right price with an unbeatable warranty, it's the Diamondback from Vortex.

But, the Diamondback isn't the only Vortex rifle scope that we approve of. The Viper PST 6-24X50 scope is a beaut to behold as well. With its illuminated EBR-1 MOA reticle, high-powered specs, and side focus, you'll be sitting quite nicely in practically any shooting scenario you find yourself in.

To compare a scope with the same specs, you'll have to check out the Nikon ProStaff 4-12X40 that costs a bit more than the Vortex. The two scopes are pretty comparable on paper with its fast focus eyepiece and optical prowess, but you'll have to weigh brand reputation between the two to decide which is best for you.

Vortex is an American favorite optics brand. They've hit the nail on the head when hunters and shooters want things done right. It seems to be a running theme that Vortex lives up to - "do it right first time, every time!"

Further Reading

Photo of author

Simon Cuthbert - Founder

Simon is an avid outdoor enthusiast and the founder of Target Tamers. He is passionate about bringing you the most up to date, accurate & understandable information on sports optics of all kinds and for all applications. Simon has contributed to notable publications online and teaches beginners the technical side of optics through his extensive library of optics guides.

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