The BFG 50's 1SK to the torso at long range is a powerful asset. The larger 1SK area compared to other snipers who have either a limited 1SK range to the torso, or only can 1SK via headshots makes the BFG 50 easier to achieve kills with. This is useful particularly against moving targets or targets at longer ranges.
The K7 is an integrally suppressed gun, but it can still equip a loudener. Adding this to the Desert Eagle XIX will make this the Loudest gun in the game, as seen in this video.