I have the S410 Extra FAC in .177. I get about 35 - 40 conistent shots before I notice a drop in POI.
The only reason why I have the FAC version is because of the flat trajectory. Not because i want to hit targets out at 50+ meters.
The barrel shroud does a decent job, but I would like to see an add-on silencer for this rifle to make it even more quiet.
D.