Rock River Arms LAR-8
- Category
- Battle Rifle
- Barrel
- 508 mm
- Weight, empty
- 4.62 kg
- Introduced
- 2005
About
What it is, and why it matters
The Rock River Arms LAR-8 is an American AR-10/SR-25-pattern semi-automatic battle rifle chambered in 7.62x51mm NATO (.308 Winchester). Introduced around 2005, its defining feature is a forged 7075-T6 aluminum lower receiver engineered to accept inexpensive FN FAL-pattern magazines (both inch and metric) in addition to Rock River's own magazines, a solution to the scarcity and high cost of AR-10/SR-25 magazines at the time. It retains a direct-gas-impingement operating system with a multi-lug rotating bolt and cylindrical bolt carrier, and adds ambidextrous magazine-release and bolt-stop controls. Rock River guarantees roughly 1 MOA accuracy with match ammunition.
Rock River Arms was founded in 1996 by brothers Mark and Chuck Larson, building a reputation on AR-pattern rifles and law-enforcement contracts before developing the LAR-8. When the company entered the .308 market, AR-10 and SR-25 magazines were both scarce and expensive, so Rock River patented a lower receiver that feeds from plentiful surplus FN FAL magazines instead, while also enabling ambidextrous controls uncommon on AR-10-pattern rifles.
The LAR-8 is offered in numerous configurations (Standard A4/Operator, Elite Operator, Varmint A4, X-Series) differing in barrel length (16-26 in), handguard, and stock. The FAL-magazine feed system was patented by Rock River Arms.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- Rock River Arms
- Category
- Battle Rifle
- Country
- United States
- Status
- In production
- Produced
- 2005
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 508 mm
- Overall length
- 1073 mm
- Weight, empty
- 4.62 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Gas operated
- Firing mechanism
- Hammer fired
- Trigger
- Two stage
- Trigger pull
- 19.0 N
- Capacity
- 20
- Magazine
- Detachable box
MaterialsEach swatch is the material itself, not a colour chosen to stand for it.
- Frame
- Aluminum
- Barrel
- Steel
- Stock
- Polymer
- Finish
- Matte black
BallisticsFrom the service cartridge, not a handload.
- Effective range
- 600 m
Trajectory
What the round does downrange
Solved from the muzzle figures and the bullet. The dashed rule is the effective range on the record, and the crosses are the steps the solver returned.
Features
What it has
What the record lists as fitted, drawn from the catalogue.
Direct impingement
Free float handguard
Picatinny rail
Ambidextrous magazine release
Ambidextrous bolt stop
Fal pattern magazine compatibility
Folding front sight
Standing
How it compares
Each figure against the firearms of the same type and cartridge that record it, or of the same type where that cartridge has too few. Positions are read to the nearest tenth.
| Measurement | This firearm | Median | Position |
|---|---|---|---|
| Empty weightAmong 86 7.62x51mm NATO battle rifles | 4.62 kg | 4.30 kg | Heavier than about 90% |
| Overall lengthAmong 85 7.62x51mm NATO battle rifles | 1073 mm | 1025 mm | Longer than about 70% |
| Barrel lengthAmong 87 7.62x51mm NATO battle rifles | 508 mm | 458 mm | Longer than about 60% |
| Magazine capacityAmong 87 7.62x51mm NATO battle rifles | 20 | 20 | Near the median |
Answers
Questions about the Rock River Arms LAR-8
How much does the Rock River Arms LAR-8 weigh?
The Rock River Arms LAR-8 weighs 4.62 kg (10.19 lb) empty.
What caliber is the Rock River Arms LAR-8?
The Rock River Arms LAR-8 is chambered in 7.62x51mm NATO.
How many rounds does the Rock River Arms LAR-8 hold?
The Rock River Arms LAR-8 holds 20 rounds, fed from a detachable box magazine.
How long is the Rock River Arms LAR-8?
The Rock River Arms LAR-8 is 1073 mm (42.2 in) long overall, with a 508 mm (20.0 in) barrel.
Who makes the Rock River Arms LAR-8?
The Rock River Arms LAR-8 is made by Rock River Arms (United States).
When was the Rock River Arms LAR-8 introduced?
The Rock River Arms LAR-8 was introduced in 2005.
How does the Rock River Arms LAR-8 operate?
The Rock River Arms LAR-8 uses a gas operated action, and its firing mechanism is hammer fired.
Compatibility
Which parts fit this firearm
Studio
Every part that mounts on this, resolved
Not a list the maker typed out: the answer comes from the mounts this firearm exposes and the interface each part needs, so it stays right when either one changes.
- Every part that mounts on any firearm in the catalogue
- Interface standards, platforms and fit overrides
- The same answers through the API and the MCP server
Requires a signed-in GunSpec account on the Studio plan. The answer is computed per part, so it is not part of the public record.
Provenance
What the record holds
Every figure above was taken from one of these pages. The confidence reflects how much of the record came from a page a claim can be checked against.
Provenance
Confidence in this record
74%
Stockists
Where to buy
Offers link straight to the shop. GunSpec never takes the order.
No shop has listed this firearm yet
Stock and prices come from the shops themselves. If you sell this firearm, you can list it and it appears here.
List a firearmMCP
Ask an assistant about it
The same record, reached the way a person asks for it rather than the way a program does.
Ask GunSpec
Works with
Point an MCP client at GunSpec and it answers from the catalogue rather than from memory. A free key covers the read tools.
API
The call that returns this record
The same fields, in the same units, from the same endpoint the page reads.
curl --request GET \ --url 'https://api.gunspec.io/v1/firearms/rock-river-lar-8' \ --header 'X-API-Key: your_key'{ "id": "rock-river-lar-8", "name": "Rock River Arms LAR-8", "manufacturer": { "id": "rock-river-arms", "name": "Rock River Arms", "countryCode": "US", "foundedYear": 1996, "website": "https://www.rockriverarms.com", "logoUrl": null, "description": null, "status": null, "defunctYear": null, "stateOwned": null, "makesFirearms": null, "parentId": null, "predecessorId": null, "createdAt": "2026-02-18 03:40:48", "updatedAt": "2026-02-18 03:40:48", "version": "c3b7d5d735f31ddaa848995a9ed6f1dc7224b54799df4e54ec5a6cdcb673a4f3" }, "category": { "id": "battle-rifle", "name": "Battle Rifle", "description": "Selective-fire rifles chambered in full-power cartridges" }, "country_of_origin": "US", "year_introduced": 2005, "barrel_length_mm": 508, "weight_empty_g": 4621, "action_type": "gas_operated"}