The Rock River Arms LAR-15M CAR A4 is a semi-automatic rifle chambered in .300 AAC Blackout, built on RRA's mil-spec-plus platform. The 16-inch chrome moly stainless steel barrel with a 1:8 twist handles both supersonic and subsonic .300 BLK loads, which makes it well-suited to suppressor use. 
 

Key Specifications 

• Model: LAR-15M CAR A4 
• Manufacturer: Rock River Arms 
• Caliber: .300 AAC Blackout 
• Barrel Length: 16 inches 
• Capacity: 30+1 rounds 
• Weight: 7.10 lbs 
• Finish: Black 
• Trigger Type: Two-stage match trigger 
• Stock Type: RRA 6-position tactical car stock 
• Sights: A2 front sight 
• Action Type: Semi-Auto 
   

Detailed Features 

 
The two-stage match trigger is one of the more notable inclusions here — it provides a cleaner, more consistent break than the standard mil-spec single-stage trigger, without requiring an aftermarket upgrade. The 1:8 twist rate stabilizes 110–220gr .300 BLK projectiles, giving you flexibility with subsonic loads if you run a suppressor. The direct impingement gas system is standard for the platform; the 6-position collapsible stock adjusts to fit different shooters or body armor setups. The A2 front sight is fixed and usable but most buyers planning to run optics will add a free-float handguard and remove it.

Owners of the Rock River Arms LAR-15M in .300 AAC Blackout generally praise RRA's build quality and the two-stage match trigger, which comes pre-installed at a price point where competitors often include a basic mil-spec trigger. Accuracy with subsonic loads gets specific mention from owners who run suppressors, with groups tighter than they expected from a factory rifle. Reliability across both subsonic and supersonic loads is consistently reported as good.

The main criticisms are weight — at 7.10 lbs, it's on the heavier end for a 16-inch carbine — and price relative to similar .300 BLK options. A few owners also note that accessories like handguards and rail systems don't always fit RRA lowers as cleanly as AR lowers from other manufacturers, due to minor tolerance differences.