Description
The precision configuration, and a barrel length the SOT SPIRE 6 range is built on. 416R stainless in the SOLGW Precision SPR contour, with SOLGW’s proprietary P3 polygonal three-groove rifling and a 1:7.5 twist. Two more inches of barrel is where the heavier six-millimeter projectiles start earning their ballistic coefficient.
At 18″ the Precision SPR takes the rifle-length gas system: lower port pressure, longer dwell, and the softest impulse of the two lengths. Note that rifle-length is not the longest system available — SOLGW’s 20″ steps up to rifle+1″ and a .875″ journal. This barrel is the 18″, on .750″. 6mm Max® keeps the unmodified mil-spec .378 (5.56) bolt face.
The low-profile gas block is installed and pinned before shipment — port alignment verified, set screws torqued to specification, and a stainless steel coiled pin through block and barrel. This length is also cataloged with the RIFLESPEED Gas Control fitted in place of the fixed block, as BBL-6MAX-B180RS-MRP.
Converted to the LMT® MRP™ barrel interface, then inspected, gauged and assembled by the Second of Ten build team to a documented standard. Installs with the MRP™ upper’s factory barrel hardware — no proprietary tooling and no permanent modification to the receiver. Headspace is gauged and recorded on the barrel inspection record before shipment.
Ships shooter ready: gas tube installed and the muzzle protected by the SOT Standard Barrel Thread Protector (CNC-machined steel, black or nitride finish), with no muzzle device fitted. Brakes, flash hiders and suppressor mounts are fitted and timed to order through the SOT Custom Shop. The protected bare thread is also the right configuration for a direct-thread suppressor. A headspaced bolt carrier group can be added and gauged to this barrel: SOT Enhanced Microbest C158 MPI DLC+, SOT Enhanced HM Defense in Black Nitride, or the SOT Enhanced Microbest Super-Stake with the Young Manufacturing HMB™ bolt.
At 18 inches this barrel builds a conventional rifle — no tax stamp, no registration and no wait. Requires 6mm Max® magazines.
Includes
- 18″ SOLGW Precision SPR barrel, converted to the LMT® MRP™ interface
- Low-profile gas block, installed, aligned, torqued and pinned with a stainless steel coiled spring pin
- Gas tube sized to the gas system, black nitride finish, installed
- SOT Standard Barrel Thread Protector, fitted (CNC-machined steel, black or nitride finish)
- Vacuum-sealed, with a Zerust® corrosion-inhibitor tube in the bore (remove before firing)
- Barrel inspection record (SOT-BIR-001)
Options
- Headspaced bolt group: SOT Enhanced Microbest C158 MPI DLC+
- Headspaced bolt group: SOT Enhanced HM Defense, Black Nitride
- Headspaced bolt group: SOT Enhanced Microbest Super-Stake with Young Manufacturing HMB™
- Muzzle devices from other manufacturers, installed and timed — for a specific muzzle device, please ask before ordering
Matching headspaced bolt
Choose a bolt above and we gauge headspace with it in this barrel and record the pairing on the barrel inspection record, so the two ship as a matched set.
Full specifications, photos and the inspection standard
Shipping: we do not ship barrel assemblies to CA, CT, DE, DC, HI, IL, MD, MA, NJ, NY, RI or WA, or to Denver, CO or Cook County/Chicago, IL. Questions? Ask your local FFL.
WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
