This particular Upper Assembly was originally a Colt 6731 Factory HBAR with a 1:9 twist barrel. After the AWB had sunset I sent the Upper to Randall Rausch at www.ar15barrels.com and had him turn down the barrel to his Featherweight contour. We left the barrel under the FSB the original diameter to avoid any issues with mechanical zero and I requested he cut the barrel length to 14.5 inches and permanently attach the Phantom FH. I also shipped Randall the GG&G Modular Free Float Forend and had him install it on the Upper. Turnaround time was quick and the price was very reasonable including reparkerizing the barrel. The workmanship is outstanding. I used this rifle in a carbine course in July 2005 and although I developed tendonitis in my support arm elbow and couldn't finish the course, I still had the opportunity to shoot approximately 400 rounds through it without any malfunctions. I can recommend Randall without hesitation.