10.5″ 300 Blackout Upper Receiver – 416R Stainless PVD Barrel | 9.7″ RG2-S Wedge Lock M-LOK
A properly built 10.5″ 300 Blackout upper should be more than a collection of parts. Component quality, dimensional consistency, proper assembly, and attention to fitment all matter.
This Mid State Firearms 10.5″ 300 Blackout upper is built around a 416R stainless steel 10.5″ barrel with a 1:8 twist, PVD finish, and 5/8″-24 muzzle threads, paired with a pistol-length gas system and a 9.7″ RG2-S Wedge Lock M-LOK handguard.
The upper receiver is a clear-anodized 7075-T6 mil-spec receiver without a forward assist, while retaining the dust cover. The clear anodized 7075 has a slight gold/tan/fde hue to it for a cool look.
Every component is selected with an emphasis on quality, fitment, and consistent tolerances. The assembly is properly installed and torqued rather than simply put together and shipped.
Built With Quality Components
Upper Receiver
- 7075-T6 aluminum
- Mil-spec configuration
- Clear anodized finish
- Forward assist omitted
- Dust cover included
Barrel
- 10.5″ length
- .300 AAC Blackout / 300 BLK
- 416R stainless steel
- 1:8 twist rate
- PVD finish
- 5/8″-24 muzzle threads
- Pistol-length gas system
Gas System
- .750″ steel gas block
- Stainless steel gas tube
- Pistol-length configuration
Handguard
- 9.7″ RG2-S Wedge Lock M-LOK rail system
- M-LOK accessory mounting interface
- Wedge-lock mounting system
Muzzle Device
- OTX 3-prong flash hider
- OTX Castle blast shield
Properly Assembled — Not Just Parts in a Box
We believe the assembly of an upper matters just as much as the individual components.
Mid State Firearms builds these uppers with attention to proper fitment, alignment, tolerances, and torque specifications. The goal is a finished upper that is correctly assembled and ready for installation rather than a collection of components that the customer has to sort out themselves.
We’ve been building and selling AR-pattern components since 2014, and our experience goes into how we select components and put them together.
Optional BCG & Charging Handle — Test Fired With Your BCG
Choose the optional BCG and charging handle when ordering and we’ll take the additional step of test firing the completed upper with the exact BCG supplied with your order.
That means the BCG that ships with your upper isn’t simply included in the box—it is used during our function check.
Our goal is simple: verify the completed upper is functioning properly before it leaves Mid State Firearms, so your upper is ready to pin to your lower and go.
Why 300 Blackout?
.300 AAC Blackout was developed around the AR-15 platform and is well suited to short-barreled configurations. The cartridge was designed to provide useful performance from shorter barrels while utilizing standard AR-15-pattern magazines and lower receivers.
A 10.5″ barrel provides a compact 300 BLK configuration while retaining enough barrel length for a broad range of commonly available .300 Blackout ammunition.
Always use ammunition specifically marked for .300 AAC Blackout and follow the ammunition and firearm manufacturer’s safety instructions. Do not use .300 AAC Blackout ammunition in a firearm chambered for a different cartridge.
Mid State Firearms: Building Since 2014
Mid State Firearms has been serving customers since 2014.
Our focus has always been straightforward: offer quality components, assemble them correctly, and stand behind what we sell.
We don’t believe customers should have to guess what they’re getting. That’s why we provide the actual specifications for the barrel, gas system, receiver, handguard, and muzzle device right here on the product page.
This upper is backed by our Limited Lifetime Warranty, giving you additional confidence in the product and in the company standing behind it.
What’s Included
This upper receiver assembly includes:
- 7075-T6 clear-anodized upper receiver
- Dust cover
- 10.5″ 416R stainless steel .300 Blackout barrel
- 1:8 barrel twist
- PVD barrel finish
- 5/8″-24 muzzle threads
- Pistol-length gas system
- .750″ steel gas block
- Stainless steel gas tube
- 9.7″ RG2-S Wedge Lock M-LOK handguard
- OTX 3-prong flash hider
- OTX Castle blast shield
BCG and charging handle are optional unless specifically selected with the configuration.
Technical Specifications
| Specification | Details |
|---|---|
| Caliber | .300 AAC Blackout / 300 BLK |
| Barrel Length | 10.5″ |
| Barrel Material | 416R Stainless Steel |
| Barrel Finish | PVD |
| Twist Rate | 1:8 |
| Muzzle Threads | 5/8″-24 |
| Gas System | Pistol Length |
| Gas Block | .750″ Steel |
| Gas Tube | Stainless Steel |
| Handguard | 9.7″ RG2-S Wedge Lock M-LOK |
| Upper Receiver | 7075-T6 Aluminum |
| Receiver Finish | Clear Anodized |
| Forward Assist | None |
| Dust Cover | Included |
| Muzzle Device | OTX 3-Prong Flash Hider |
| Blast Shield | OTX Castle |
| BCG | Optional |
| Charging Handle | Optional |
| Warranty | Limited Lifetime |
Frequently Asked Questions
What caliber is this upper?
This is a .300 AAC Blackout (300 BLK) upper receiver assembly with a 10.5″ barrel.
What is the barrel twist rate?
The 416R stainless steel barrel has a 1:8 twist rate.
What are the muzzle threads?
The barrel uses 5/8″-24 muzzle threads.
What gas system does this upper use?
This configuration uses a pistol-length gas system with a .750″ steel gas block and stainless steel gas tube.
Does the upper have a forward assist?
No. This configuration uses a 7075-T6 upper receiver without a forward assist.
Does it have a dust cover?
Yes. A dust cover is included.
How long is the handguard?
The RG2-S Wedge Lock M-LOK handguard is 9.7″ long.
Does it come with a BCG and charging handle?
The BCG and charging handle are optional. If you add them to the order, Mid State Firearms will test fire the completed upper using the exact BCG supplied with that order.
Is the upper test fired?
When ordered with the optional BCG and charging handle, the completed upper is test fired with that specific BCG to verify function before shipment.
Can I use this upper with my existing lower?
This is an AR-pattern .300 Blackout upper assembly intended for use with a compatible lower receiver. Compatibility can depend on the specific lower, components, and configuration. Always verify compatibility and follow applicable manufacturer’s instructions before assembly or use.
Who builds this upper?
The upper is assembled by Mid State Firearms, which has been in business since 2014.
What warranty does it have?
This product is covered by the Mid State Firearms Limited Lifetime Warranty, subject to the terms and exclusions of the warranty.
Quality Components. Proper Assembly. Backed by Mid State.
Mid State Firearms has been building and supplying AR components since 2014. We put an emphasis on using quality components and assembling them correctly, because the details matter.
This 10.5″ 300 Blackout upper combines a 416R stainless PVD-finished barrel, pistol-length gas system, 9.7″ RG2-S Wedge Lock M-LOK handguard, 7075-T6 clear-anodized upper receiver, and OTX muzzle-device system into one complete upper assembly.
Add the optional BCG and charging handle and we’ll test fire the upper with that exact BCG before it ships.
That’s the difference between buying a box of parts and buying a properly assembled upper from a company that has been doing this since 2014.
sound of freedom – This was a great set up. I loved being able to customize the set up. Only issue I had was my own fault as a newb to building these. I used a heavy barrel in a slim hand guard. It makes adding attachments tough with clearances. Hoping someday to also get an AR10 from here.