Gas operated and recoil operated firearms all have lots of noise issues besides the muzzle blast. Also need to find subsonic ammo as supersonic crack (bullet breaking the sound barrier) also makes a lot of noise. A bolt action rifle with subsonic ammo is probably the best candidate. Most silencers have a Kevlar or hard rubber buffer system for noise reduction and both wear out quickly, so I never thought that silencers were a very good investment.
Dave
Dave