Kb mfg 1-9 mpi barrel in Rock River Arms upper

[Jarhead031197]

I recently bought a rock river arms upper with barrel stamped kb mfg 1-9 mpi, can anyone tell me info about quality of barrel, company contact or any details of their use of these barrels

 

[MarshallDodge]

According to this article, Rock River barrels are made by Wilson, and then final chambered at RR.

 

[Skylerbone]

KB was a spin-off of Model 1 Sales (divorce) and I believe now defunct. They were a low cost option with decent reputation for quality. I don’t know which RRA Upper you have but my guess might be that someone decided they wanted a different barrel length or contour and swapped.