I have started to replace broken HS805BB with bluebird BMS L530MG (hobbyking). I have one for my bicep and another one for the neck. The bicep initially worked fine until the horn adapter started to slip (the lower arm is a heavy bugger). I recommend therefore metal servo horns with the bluebird servo. You need to order them separately. Unfortunately the servo spline type is not documented well, HS805 has a D1 spline (15 teeth) and the bluebird has a standard C1 spline (24 teeth).