I am selling my Prometheus tightbore barrel that I never really used for $50. It has been just sitting in my closet, so I want to sell it to someone who can appreciate this precision product. I'm throwing in for free a Tokyo Marui mid-capacity M4 AEG clip as well. Although this barrel is "used", it has very minor scratches on the outside and is as smooth and glass-like on the inside as the day I bought it. The inner diameter is 6.03mm and it's length is 509mm, suitable for M16 and AUG rifles.