Mrp-L Quad 5.56/300 Blk 13.25'' Assembled Upper Receiver

The LMT Defense MRP-L Quad 5.56/300 BLK 13.25" assembled upper receiver brings monolithic precision to your rifle build. This is a rifle-length receiver engineered to accept barrels from 14.5" to 20", making it a versatile platform for everything from mid-range carbines to long-distance builds in both 5.56 NATO and .300 Blackout. The single-piece forged aerospace aluminum construction eliminates gaps between receiver and handguard, delivering the rigidity and repeatability serious shooters demand.

LMT's proprietary barrel retention system uses two T-30 Torx bolts accessible from the right side—no special tools, no guesswork. The integrated quad rail runs at the 3, 6, and 9 o'clock positions, giving you mounting flexibility for optics, lights, and other accessories without compromise. Five QD sling attachment points let you configure carry and support your way. This is a no-compromise upper built for shooters who want precision and modularity in one package.

Note: This is an assembled upper receiver only. The barrel assembly is sold separately and must be the LMT monolithic barrel system designed for the MRP platform, which features a low-profile gas block and straight gas tube. If you're building a precision rifle or upgrading an existing platform, this receiver gives you the foundation that scales with your ambition.

Key Features

• Monolithic forged aerospace aluminum construction—receiver and handguard as one piece
• Proprietary two-bolt barrel retention system (T-30 Torx key only)
• Rifle-length platform compatible with 14.5" to 20" barrels
• Integrated quad rail (3, 6, 9 o'clock) for optics and accessory mounting
• Five QD sling swivel attachment locations
• Supports 5.56 NATO and .300 Blackout (with appropriate LMT barrels)

Specifications

Frequently Asked Questions

What barrels are compatible with the MRP-L Quad upper receiver?

This receiver requires the LMT monolithic barrel assembly designed for the MRP platform. The barrel system includes a low-profile gas block and straight gas tube. The receiver accommodates barrels from 14.5" to 20" in length. Check LMT's current barrel offerings for your desired caliber and length.

Is a barrel included with this upper receiver?

No. The barrel assembly is sold separately. You will need to source an LMT monolithic barrel assembly compatible with the MRP platform in your choice of caliber and length.

What calibers does this upper receiver support?

The MRP-L platform supports 5.56 NATO and .300 Blackout, along with 6.8 SPC and .204 Ruger (with appropriate LMT barrel assemblies). The specific barrel you choose determines your caliber.

Do I need special tools to install a barrel on this receiver?

No. The barrel is retained by two T-30 Torx bolts accessible from the right side of the receiver. A standard T-30 Torx key is all you need—no proprietary tools required.