http://www.pbase.com/illusive_airsof..._armament_sr15
No real problems, although you might need a delta ring key to help tighten the ring/nut.
Quality is great.
Mounting accessories is no problem, although sometimes a tiny bit loose for real steel accessories.
No mounting instructions exist unless you get the VFC/GB-Tech version. Only problem with that one is that the markings are incorrect.