Here is what most .300 Blackout pistol builders learn too late. A 7 to 9 inch barrel is the cartridge’s natural home, but it also means your supersonic loads give up speed and your subsonic loads drop like a stone.
The .300 Blackout was designed around short barrels, and it works very well in them. Even so, a 110 grain supersonic load from a 9 inch barrel runs around 2,000 feet per second, and subsonic loads sit near 1,000.
That second number is the one that matters for your optic. A subsonic 220 grain bullet drops a foot or more by 150 yards, so you are building a close range tool, not a precision rifle.
The pistol format adds its own constraints. A short, handy build with a brace or a short stock is often front heavy once you add a suppressor, so a light optic keeps the balance manageable.
Here is the one thing that separates a good choice from a poor one. Choose an optic that is light, fast, and forgiving of head position, and skip the big objective and the long zoom.
A red dot is hard to beat on a pistol build. It is the lightest option, it is quick to find, and it is forgiving when your head position varies on a brace or a short stock.
If you want some reach, a 1 to 6x scope covers out to 150 yards, and a fixed 3x prism adds a little magnification in a tiny package. Either works well on a short barrel.
A word on the law, because it matters. Rules about braces and shouldering a pistol have changed more than once and differ by state, so confirm current law before you build or shoot from the shoulder.
Here is the lineup. The Holosun HS510C is the best all around pick, the Vortex Strike Eagle 1 6×24 is the flexible range choice, and the Primary Arms SLx 1 6×24 is the best value.
The Holosun HS403B is the budget pick, and the Primary Arms SLx 3x MicroPrism is a fixed power alternative.
Best Optics for 300 Blackout Pistol Build Comparison
| # | Image | Name | Key Features | Check Price |
|---|---|---|---|---|
| 1 |  |
Holosun HS510C | Open reflex, large window, solar failsafe | Check Price |
| 2 |  |
Vortex Strike Eagle 1 6×24 | True 1x, illuminated reticle, fast target acquisition | Check Price |
| 3 |  |
Primary Arms SLx 1 6×24 | Illuminated reticle, true 1x, strong value | Check Price |
| 4 |  |
Holosun HS403B | Simple red dot, long battery life, low price | Check Price |
| 5 |  |
Primary Arms SLx 3x MicroPrism | Fixed 3x prism, compact, illuminated reticle | Check Price |
In Depth Reviews
Each optic below was chosen for a short barreled .300 Blackout pistol build. As you read, think about balance, head position, and your real distances.
#1 Holosun HS510C – Best Overall
If you want one optic for a .300 Blackout pistol, start here. It is light, fast, and well matched to the distances the cartridge does best.
The large, open window makes the dot easy to find, even when your head position is not perfect. That matters on a pistol with a brace or a short stock.
The multiple reticle system lets you run a 2 MOA dot for precision, a 65 MOA ring for fast close work, or both together. The ring makes the optic very quick on a close target.
Here is a detail most buyers miss. A red dot’s point of aim shifts very little with head position, so it forgives the inconsistent cheek weld you get from a brace.
The solar failsafe tops up the battery, and shake awake turns the dot on when you move the pistol. Wipe the open window, because a suppressed or short barrel build can spit carbon.
Who should buy this? Builders who want a light, fast optic for a short barrel. Who should skip it? Shooters who want to see small targets at distance.
It earns the top spot because it fits the build so well.
Key Features
| Feature | Specification |
|---|---|
| Reticle | 2 MOA dot with 65 MOA ring, selectable |
| Battery | Check current specification |
| Window | Large, open reflex |
| Solar Failsafe | Yes |
| Magnification | 1x |
| Warranty | Covered by Holosun’s 10 year warranty |
Pros
- A large window makes the dot easy to find
- It is light and fast, which keeps a short pistol balanced
- Forgiving of head position changes on a brace or short stock
- Covered by Holosun’s 10 year warranty
Cons
- It has no magnification
- An open window can collect carbon, suppressed
- It is less precise past 100 yards
Our Take
If you want a light, fast optic for a short barrel, the Holosun HS510C is worth a closer look. It delivers a large window and a multiple reticle system, and it is covered by Holosun’s 10 year warranty.
#2 Vortex Strike Eagle 1 6×24 – Best for Flexible Range
If you want a little reach as well as close range speed, a 1 to 6x scope is the answer. This one gives you both in a tough, proven package.
At 1x, you shoot with both eyes open, which helps a lot on a short pistol. At 6x, you can place a careful shot at 150 yards, which covers everything the build does well.
Here is a detail most buyers skip. Printed BDC marks are built for supersonic loads from a longer barrel, so build your own holdover chart for your pistol and your subsonic load.
The illuminated reticle helps in dark cover and at the edges of the day. The scope is tough and carries Vortex’s warranty.
It is heavier than a red dot, so the pistol will be more front heavy. Consider a lighter handguard or a shorter suppressor to offset it.
Who should buy this? Builders who want some reach in a short barreled pistol. Who should skip it? Builders who want the lightest possible setup.
It lands second because it adds weight to a handy build. For the right shooter, the reach is worth it.
Key Features
| Feature | Specification |
|---|---|
| Magnification | 1 to 6x |
| Objective Lens | 24mm |
| Tube Diameter | 30mm |
| Reticle | Illuminated BDC style |
| Weight | 16 ounces |
| Warranty | Vortex VIP: unconditional, lifetime, and transferable |
Pros
- A true 1x low end gives red dot speed at close range
- The 6x top end covers shots out to about 150 yards
- An illuminated reticle helps in dark cover
- Backed by Vortex’s VIP warranty: unconditional, lifetime, and transferable to the next owner
Cons
- It adds weight to a short pistol
- Printed holdover marks will not match a subsonic trajectory
- The eye box shrinks at higher magnification
Our Take
If you want a little reach for your pistol build, the Vortex Strike Eagle 1 6×24 is worth a closer look. It delivers fast target acquisition and carries Vortex’s VIP warranty: unconditional, lifetime, and transferable.
#3 Primary Arms SLx 1 6×24 – Best Value
If you want an illuminated low power scope at a fair price, this is a strong option. It has a true 1x low end and a reticle that is easy to see.
The illuminated reticle is the standout. When your head position varies on a brace, a bright reticle is easier to pick up than a thin black one.
The 6x top end gives you enough reach for a careful shot at 150 yards. For a short barrel and subsonic loads, that is about the practical limit.
Here is a detail most buyers overlook. Some Primary Arms reticles are designed around .300 Blackout, so check whether a matching option exists for the model you buy.
The scope is a little heavier than a red dot, but the extra weight is minor on an AR. Primary Arms backs it with a lifetime warranty.
Who should buy this? Builders who want an illuminated reticle at a fair price. Who should skip it? Builders who want the lightest possible setup.
It lands third because it overlaps with the Strike Eagle. For the right builder, it is an excellent value.
Key Features
| Feature | Specification |
|---|---|
| Magnification | 1 to 6x |
| Objective Lens | 24mm |
| Tube Diameter | 30mm |
| Reticle | Illuminated, second focal plane |
| Weight | 16 ounces |
| Warranty | Backed by Primary Arms’ lifetime warranty |
Pros
- A true 1x low end lets you shoot with both eyes open
- An illuminated reticle helps in dark timber and at the edges of the day
- Some reticle options are designed for .300 Blackout, so check the model
- Backed by Primary Arms’ lifetime warranty
Cons
- It overlaps with the Strike Eagle for many builders
- Reticle marks may not match a subsonic trajectory
- It is heavier than a red dot
Our Take
If you want an illuminated low power scope at a fair price, the Primary Arms SLx 1 6×24 is worth a closer look. It delivers a bright reticle and a true 1x low end, and it is backed by Primary Arms’ lifetime warranty.
#4 Holosun HS403B – Best Budget Pick
A pistol build adds up, so a sensible optic keeps the total in check. This red dot gives you the basics at a very low price.
It is a simple, tough red dot with a long battery life. There is no fancy reticle system, just a dot that you can find and shoot well.
Here is a detail worth knowing. A simple dot is often easier to learn than a multiple reticle system, and for a first pistol build it is a good choice.
The tradeoff is features. You do not get the solar failsafe or the large window of the HS510C, so you give up some flexibility for the lower price.
The optic is light, which helps a short pistol stay balanced. It is also covered by Holosun’s warranty.
Who should buy this? Budget minded builders who want a simple, reliable dot. Who should skip it? Builders who want a ring reticle or a solar failsafe.
It lands fourth because it has fewer features. For the price, it does the job well.
Key Features
| Feature | Specification |
|---|---|
| Reticle | Single dot, check current size |
| Battery | Long life, check current specification |
| Window | Open reflex |
| Solar Failsafe | Check current specification |
| Magnification | 1x |
| Warranty | Covered by Holosun’s 10 year warranty |
Pros
- A very low price makes it a sensible choice for a first build
- A simple dot is quick to learn and quick to find
- It is light, which keeps a short pistol balanced
- Covered by Holosun’s 10 year warranty
Cons
- It has fewer features than the HS510C
- It has no ring reticle for very fast close work
- The window is smaller than the HS510C
Our Take
If you want a simple, low cost red dot, the Holosun HS403B is worth a closer look. It delivers a reliable dot at a very low price, and it is covered by Holosun’s 10 year warranty.
#5 Primary Arms SLx 3x MicroPrism – Best Fixed Power Alternative
If you want a little magnification without the weight of a variable scope, a compact prism is a good compromise. This one gives you a fixed 3x in a very small package.
A prism has a short, compact body and generous eye relief, which suits a short barreled pistol well. The illuminated reticle is etched in glass, so it works even when the battery dies.
Here is a detail most buyers skip. The reticle is calibrated for a specific cartridge, so check that it suits .300 Blackout or build your own holds.
The 3x magnification helps you see targets at 100 to 150 yards, which is more than a red dot offers. It is a very good choice for a short, handy pistol.
The tradeoff is flexibility. You cannot dial down to 1x, so close shots are a bit slower than with a variable scope.
Who should buy this? Builders who want a compact, fixed power optic. Who should skip it? Builders who want a true 1x for very close work.
It lands fifth because it is a specialist. For the right builder, it is a good compromise.
Key Features
| Feature | Specification |
|---|---|
| Magnification | 3x fixed |
| Type | Compact prism |
| Reticle | Illuminated, etched in glass |
| Eye Relief | Generous, suited to short barrel builds |
| Weight | 11 ounces |
| Warranty | Backed by Primary Arms’ lifetime warranty |
Pros
- A compact, light prism keeps a short pistol handy
- An etched reticle works even if the battery dies
- A fixed 3x gives you more reach than a red dot
- Backed by Primary Arms’ lifetime warranty
Cons
- You cannot dial down to 1x for very close shots
- The reticle is calibrated for a specific cartridge
- Magnification is fixed, so there is no flexibility
Our Take
If you want a compact, fixed power optic, the Primary Arms SLx 3x MicroPrism is worth a closer look. It delivers a light, tough package and is backed by Primary Arms’ lifetime warranty.
Did You Know? The .300 Blackout was designed to work in short barrels, and it stays efficient in barrels as short as 8 or 9 inches. That is why it became so popular for pistol builds, where a 5.56 round would lose much more of its performance.
Conclusion
You now know a .300 Blackout pistol is a close range tool, and that a light, fast optic matters more than high magnification on a short, handy build.
You also know subsonic loads drop a foot or more by 150 yards, so building your own holdover chart is worth the afternoon at the range.
For most .300 Blackout pistol builders, the Holosun HS510C is the right choice. It gives you a large window, a fast reticle, and a warranty that covers a full decade.
It earns the top spot because it fits the build so well.
If you want some reach, the Strike Eagle 1 6×24 is the flexible pick.
For one who wants value, the Primary Arms SLx 1 6×24 is a strong choice.
If you want to spend less, the Holosun HS403B is a sensible dot. If you want a little magnification in a tiny package, the SLx 3x MicroPrism is a nice compromise.
Before you order, confirm the current laws that to your build, and mount the optic for a comfortable head position. Then confirm your zero, and with the suppressor attached if you shoot subsonic.
Whichever optic you pick, you are building a short, capable pistol. Take your time, stay legal, and enjoy the shooting.
Richard Brown is a long-range shooting enthusiast and competitive shooter with extensive experience in scopes across multiple disciplines. He hunts regularly across the Midwest and has built his expertise through years of hands-on testing in both competitive shooting and hunting. Richard also instructs youth rifle shooting, which has given him perspective on scopes at every price point and skill level. He combines technical knowledge with practical field experience to provide honest reviews – contact me