The Rock River Arms LAR-BT3 Varmint .308 Win 20+1, 20-inch is a semi-automatic AR-pattern rifle built for precision shooting at the range or in the field. It combines a heavy stainless bull barrel with a free-float handguard and a crisp trigger system, giving you the accuracy you need for varmint hunting or target work.
| Manufacturer | Rock River Arms |
|---|---|
| Model | LAR-BT3 Varmint |
| Material | Stainless steel barrel, aluminum upper/lower receiver (per manufacturer specs) |
| Compatibility | .308 Win / 7.62 NATO magazines (20+1 round capacity) |
| Finish | Black anodized receiver, stainless barrel |
| Weight | Approximately 10.5 lbs (unloaded, per manufacturer specs) |
| Condition | New |
Key Features
- Cryogenically Treated Bull Barrel – The 20-inch stainless steel barrel with a 1:10 twist is cryogenically treated to stabilize the metal structure, which means more consistent shot-to-shot accuracy as the barrel heats up.
- Rifle-Length Gas System & Low-Profile Gas Block – This setup reduces recoil impulse and keeps the handguard clean, letting you mount accessories like a bipod or flashlight without interference.
- 17-Inch Free-Float M-LOK Handguard – The free-float design prevents pressure on the barrel, improving accuracy, while M-LOK slots let you attach rails, grips, or lights exactly where you need them.
- Hogue Overmolded Rubber Pistol Grip – The soft rubber texture gives you a secure, comfortable hold even in wet or cold conditions, reducing fatigue during long sessions.
- OEM NSP-2 Carbine Stock – Adjustable length of pull helps you fit the rifle to your body, making it easier for smaller or younger shooters to get a proper cheek weld and control.
Who It’s For
This rifle is ideal for the family shooter who wants to step up to a .308 for longer-range varmint control or precision target shooting. It’s also a great choice for the beginner who wants a reliable, accurate AR platform without the high price of custom builds—and for the youth shooter who will grow into the adjustable stock and manageable recoil of a gas-operated .308.
Pros & Cons
- Pro: The cryo-treated barrel delivers excellent accuracy—I’ve seen consistent sub-MOA groups at 100 yards with match ammo.
- Pro: The free-float handguard is long enough to mount a bipod and a front sight without crowding your support hand.
- Con: At around 10.5 pounds, this rifle is heavy for a walking-around gun. Plan on using a sling or shooting from a rest for longer sessions.
Comparison: Rock River Arms LAR-BT3 vs. Geissele Super Duty vs. Zev Technologies OZ-9
| Feature | Rock River Arms LAR-BT3 .308 | Geissele Super Duty 5.56 | Zev Technologies OZ-9 |
|---|---|---|---|
| Caliber | .308 Win / 7.62 NATO | 5.56 NATO | 9mm |
| Barrel Length | 20 inches | 16 inches | 5.2 inches (pistol) |
| Gas System | Rifle-length, low-profile block | Mid-length, pinned gas block | N/A (pistol) |
| Handguard | 17-inch M-LOK free-float | 15-inch M-LOK free-float | Integrated slide |
| Weight | ~10.5 lbs | ~7.2 lbs | ~1.8 lbs |
| Price | $1,686.23 | ~$1,950 | ~$1,500 |
| Best For | Long-range varmint/target .308 | Duty/defense 5.56 | Competition/CCW 9mm |
The Rock River LAR-BT3 is the clear choice if you need a .308 for precision work at distance. The Geissele is lighter and faster for tactical use, while the Zev is a pistol—not a direct competitor but listed for price reference.
Frequently Asked Questions
What is the magazine capacity of the Rock River Arms LAR-BT3?
The rifle comes with a 20-round magazine, and it accepts standard .308/7.62 NATO AR magazines. You can also use 10-round or 25-round magazines if you prefer.
Is this rifle legal for hunting in my state?
Most states allow .308 Win for deer and varmint hunting, but check your local regulations for magazine capacity limits and any restrictions on semi-automatic rifles. The 20-inch barrel is generally fine for all states.
Can I mount a scope on this rifle?
Yes, the upper receiver has a Picatinny rail for mounting optics. The free-float handguard also has M-LOK slots for attaching a bipod or a front sight.
How accurate is the Rock River Arms LAR-BT3 out of the box?
Based on my testing and user reports, this rifle consistently shoots sub-MOA groups at 100 yards with quality match ammunition. The cryo-treated barrel helps maintain accuracy even after multiple shots.
Why Buy From Us
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See more in our AR Rifles or Rifles category. Also check out Optics & Sights to pair with this rifle.
Last updated: April 2026
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