Firearms Republic
The PSA 8.5″ .300 AAC Blackout Upper is the mainstream answer to a simple question: how cheaply can an AR pistol lower become a suppressed 300 AAC Blackout gun? At $220–320 – the low end for the bare upper, the high end with a bolt carrier group and charging handle – it comes from one of the largest AR makers, with a nitride barrel and a 7″ free-float M-LOK rail on the reference version reviewed here. It competes head to head with the Radical Firearms 8.5″ upper, and the difference between them is mostly choice and support.
| Specification | Details |
|---|---|
| Barrel Length | 8.5″ |
| Barrel Twist | 1:7 (some versions 1:8 – check the listing) |
| Barrel Contour | Heavy profile, pistol-length gas |
| Barrel Material | 4150V chrome moly vanadium, nitride |
| Weight | ~3.0 lbs (upper assembly) |
| Overall Length | ~17″ (upper) |
| Upper Receiver | Forged 7075-T6, A3 flat top, M4 feed ramps |
| Trigger | Not included – uses the lower’s trigger |
| Magazine | Standard AR-15 PMAG .300 BLK |
| Street Price | ~$220 bare / ~$320 with BCG and charging handle |
| Handguard | 7″ lightweight Hex M-LOK, free-float |
| Threaded Barrel | 5/8×24 per PSA listings, A2 flash hider fitted |
| BCG (complete version) | Carpenter 158 bolt, full-auto profile |
Quick Verdict
✓ Best for: Budget AR pistol builds and suppressor hosts in .300 BLK
✓ Price: $220–320 street
✓ Key strength: Free-float M-LOK rail and nitride barrel at an entry price
✗ Not ideal for: Precision work or heavy duty use without a better BCG and trigger
Real-World Performance
The 8.5″ barrel is close to the ideal length for subsonic 300 Blackout. Federal 220gr OTM runs about 1,010 fps for 498 ft-lbs, essentially the same as from a longer barrel, because subsonic loads were designed around short barrels. Supersonic loads give up velocity: Hornady 110gr V-Max drops to roughly 1,850–1,900 fps, which is defense-adequate inside 75 yards but not a hunting setup beyond that. The heavy-profile barrel and pistol-length gas system are built around exactly this use.
Accuracy depends mostly on the lower. With a quality trigger, expect 1.0–1.5″ groups at 50 yards with subsonic ammunition, and worse with a mil-spec trigger. The free-float rail helps because nothing touches the barrel when you rest the pistol on a bag. A budget BCG and barrel mean you should not expect sub-MOA consistency – this is an inexpensive way into the caliber, not a precision build.
Applications & Use Cases
Budget suppressed pistol: An upper at $220–320, a pistol lower, and a suppressor keeps a complete suppressed .300 BLK pistol near $1,000 before optics. Verdict: one of the cheapest credible routes into the caliber. Caliber evaluation: If you already own a pistol lower, the upper lets you try 8.5″ .300 BLK subsonic before spending $1,500 on a premium platform. Verdict: a low-risk way to sample the cartridge.
Home defense compact: At 8.5″, this is about as compact as .300 BLK gets, and 220gr subsonic loads carry less overpenetration risk than typical 5.56 defensive loads. Verdict: viable with the right ammunition and a suppressor. Second upper for an existing lower: Already running a 5.56 pistol lower? The upper adds .300 BLK capability for the cost of one part. Verdict: a cost-effective way to add a caliber to a platform you own.
Ergonomics & Handling
At roughly 3.0 lbs and 17″ long, the upper balances light and compact on a typical pistol lower with a brace. The 7″ lightweight M-LOK rail leaves room for a light or a short grip without crowding the support hand near the muzzle. The A2-style flash hider adds length and is easy to remove when you mount a suppressor.
Manual of arms is standard AR-15, so anyone coming from a 5.56 pistol is running it within minutes, and PMAG .300 BLK magazines seat and drop free like any AR magazine. One safety point: mark your .300 BLK magazines clearly, because they look like 5.56 magazines and a .300 BLK round can chamber in a 5.56 rifle with dangerous results.
Aftermarket & Upgrade Path
Because this is standard AR-15 architecture, the aftermarket is essentially unlimited. The first practical upgrade is removing the flash hider to use the 5/8×24 thread for a suppressor. An adjustable gas block such as the SLR Sentry ($65) is worth adding for suppressor tuning and smoother subsonic cycling, since the stock setup has no adjustment. If you plan heavy use, a quality BCG ($80–120) is a sensible swap.
For precision subsonic work, a Geissele SSA trigger ($240) in the lower matters more than anything on the upper. PSA also sells lowers, parts, and complete pistol kits (an 8.5″ nitride kit with furniture is listed around $460), so you can order the whole build in one place. A suppressor such as the SilencerCo Omega 300 ($800) completes the package.
Pros & Cons
Strengths:
✓ 7″ free-float lightweight Hex M-LOK rail on the reference version
✓ Nitride barrel finish resists corrosion better than phosphate
✓ Forged 7075-T6 upper receiver
✓ Carpenter 158 bolt in the BCG version
✓ Available bare (~$220) or complete with BCG and handle (~$320)
✓ Large support network and parts catalog
✓ ~3.0 lbs keeps the pistol light
Limitations:
✗ Several 8.5″ variants (twist, finish, handguard) make it easy to order the wrong one
✗ Budget-tier BCG and barrel compared with premium options
✗ Needs a pistol lower, or an SBR registration if used with a rifle stock
✗ A2 flash hider must come off before mounting a suppressor
✗ No adjustable gas block included
✗ Popular versions often go out of stock
✗ Supersonic velocity of ~1,850–1,900 fps limits range to about 75 yards
Competitors & Alternatives
| Feature | PSA 8.5″ .300 BLK | Radical Firearms 8.5″ | BCA 10.5″ .338 ARC | CMMG Banshee MK4 |
|---|---|---|---|---|
| Price | $220–320 | $249–329 | $309.95 | $1,499–1,699 |
| Weight | ~3.0 lbs | ~2.8 lbs | ~3.0 lbs | ~5.4 lbs |
| Trigger | Not included | Not included | Not included | Included |
| Magazine | PMAG .300 BLK | PMAG .300 BLK | Proprietary .338 ARC | PMAG .300 BLK |
| Accuracy | 1.0–1.5″ @ 50 yd | 1.0–1.5″ @ 50 yd | N/A (different caliber) | 1.5–2.0″ @ 50 yd |
The Radical Firearms 8.5″ .300 AAC Blackout Upper sits in the same price band with a free-float M-LOK rail and a BCG included, so the choice comes down to PSA’s wider selection and support network versus Radical’s simpler single package. The CMMG Banshee MK4 .300 BLK is a complete RDB pistol for roughly $1,200 more – worth it once you have confirmed you like the caliber. The BCA 10.5″ .338 ARC upper offers more subsonic energy at a similar price, but gives up the ammo availability .300 BLK enjoys.
Who Should Buy This
Ideal for AR pistol owners who want an inexpensive .300 BLK upper from a large retailer with dependable parts support. It is also a strong fit for budget suppressor builders who want a free-float rail at an entry price, and for shooters who want to test 8.5″ .300 BLK subsonic before committing to a premium platform. Look elsewhere if you need sustained duty reliability or precision – step up to the CMMG Banshee MK4 .300 BLK or upgrade the BCG. If you want the simplest package, the Radical Firearms 8.5″ .300 AAC Blackout Upper includes the BCG at a similar price.
Frequently Asked Questions
Can I put this on any AR-15 lower?
Only on a pistol lower, or on an SBR you have registered. This is a pistol-length gas system, not a rifle build, and rules on braces and short-barreled rifles change, so confirm current ATF guidance and your state law.
Does it come with a BCG and charging handle?
It depends on the version. The bare upper runs about $220, while the version with a BCG and charging handle runs about $320, so check the listing before you order.
Can I mount a suppressor?
Yes, after removing the A2-style flash hider. PSA lists a 5/8×24 thread on its .300 BLK uppers, so confirm the thread on your version and match it to your suppressor.
Is a 1:7 twist a problem for .300 Blackout?
No, both 1:7 and 1:8 are common .300 BLK twists and stabilize the full range of bullet weights. The heavy 220gr subsonic loads that suit this barrel length are not an issue.
How accurate is it?
Expect about 1.0–1.5″ groups at 50 yards with subsonic ammo and a decent trigger. Results depend heavily on the trigger in your lower and on the stock BCG.
Which PSA 8.5″ version should I buy?
The nitride 1:7 version with the 7″ free-float M-LOK rail is the best value pick. PSA sells several variants with different twists, finishes, and handguards, so check each listing carefully.
Also worth a look: the PSA 9″ M-LOK .300 AAC Blackout Pistol if you want a complete pistol, and the Faxon Firearms 16″ Gunner .300 AAC Blackout Upper if you want a lighter 16″ carbine.
Final Verdict
The PSA 8.5″ .300 AAC Blackout Upper is a sensible, low-cost way into a suppressed .300 BLK pistol. It will not match a premium BCG or a tuned complete rifle, but a free-float rail and a nitride barrel at $220–320 are hard to argue with.
For anyone who already owns a pistol lower and wants to try .300 Blackout without a four-figure commitment, it delivers the core functionality at a price that makes experimentation low-risk.
