Our take: The Sapien Arms performance 6.03mm series of tightbore barrels are the newest tightbores out on the market. They feature a heavy metal Ni (nickel) coating for high lubricity and performance, and increase performance (power) an average of 15% with installation.
The super slick Heavy Metal Nickel Finish strengthens and protects the barrel, while reducing friction (conserves velocity & back spin). This 509mm barrel fits most full length M16 and AUG metal gearbox AEGs.
Precision manufactured in the USA, each barrel is HAND TESTED for tolerance and to ensure quality.
Note: Ready to use right out of the box, though professional installation is recommended/may be required. Please use only ultra high-quality precision seamless BBs in your gun after installing this barrel, as inferior grade BBs (i.e. BBs from sporting goods stores) WILL jam inside this barrel.