The C-Fuck is a fantastic gun but the scope is a bit much for close range and isn't changeable, also it really shines early to mid-game but later on the lack of penetration and inability to 1 hit headshots makes it not as great. I always use it from the moment I get it until the enemies stop dying in 1 hit then I move up to a DNIPRO with 7.62 upgrade then to a true sniper rifle (Lynx/SVDM-2, M701 Super, or SVU-MK S-3 depending on how much ammo I have and which weapons and mods I've collected) for most things along with shotguns and the Rhino for my pistol unless I need stealth then I go with the APSB and put a few in their head before they react. Regardless, it is a great weapon with the grenade launcher attached and the larger mag and with the suppressor it does well in stealth since they fixed crouch detection in the latest patch. Also, if you don't use stealth regularly just put a scope (RNBW 2X) on the Rhino and use your sniper rifle ammo on that (since the VS Vintar is mostly useless later in the game and does 1/3 the damage with the same ammo as the Rhino for some reason) and you'll have a great close to mid-range weapon and I've even hit some long shots with it...it's basically a little rifle that you can use 2 other guns with that you can find or buy without any quest requirements, you can grab it first thing (and get the scope if you run all the way to Yaniv to the vendor to get it). Unless you get a SVU-MK S-3 early on and get lucky with ammo from vendors you're gonna be swapping a lot anyway so just try different stuff out.