I'm mainly just fishing around for opinions, but I did note that going by the strictest sense of the rules you can do silly things like the above, or silencing a railgun (where the noise is fromt he bullet screaming past at mach 5 not the initial explosion). However, it's got me thinking about how this could be done and what weapons it could be done with. So, here's a list of ideas: Chemical Firearms: both work just fine with modern technologies (although to be anal, a flash suppressor is to stop the shooter from seeing the flash, not the target) Railguns: Flash-suppression should be of minimal need (would a railgun produce a flash?), silencing.... Well they've made a plane that can go supersonic without creating a sonic boom, can the some thing be done with a railgun round? Lasers: Flash suppression seems to be null and void (the beam's invisable unless you have enhanced vision), any noise made would be at the target end (rapid heating/expansion effects), so I'd argue no to that either. Microwave Guns: Don't see the need for either (although it should go 'bing!' when the target's cooked :P). Particle Beam: Invisable apparently... I would have thought that in atmo at least it would have sparked and glowed from atmospehric interaction... Still going to go bang at the other end though. Plasmaguns: You're throwing a ball of really hot ions at something, it's going to glow like a mother and prolly crackle and carry on whilst it's at it. I'm going to say silencing/flash suppressing that is pretty much impossible. Seekers: Maybe specialised ammo using turbines/compressed gas for propusion instead of chemical rockets... Dunno how small you could make that or how efficient it would be though. Electrolasers: I honestly have no idea. are they invisable like a laser, or do they spark as you throw the electric current down them? Buzzer: Don't see how it'd be hard to silence, and unless it was a deliberate function I don't see why nanobots would produce light. Might be a big dark blotch though. Freezer/Torch/Sprayer: In all cases your spreading liquid (probably a lot of it) at high pressure, in one case the liquid's also on fire. It's going to be pretty obvious no matter which way you cut it. Shard weapons: Depends on the drive mechenism. If the wepons use a low-power railgun or coilgun mechenism, then I don't see why it would make much noise or flash at all. If it's chemical, I see it being like silencing a shotgun, ie. it doesn't work to well. As far as I'm aware you can flash-suppress a shotgun without too much issue, so I don't see any problems there if that's the case. Vortex Ring Gun: Well it's chemical, the description sums that up. However, the gun seems fairly relient on barrel dynamics and both silencers and flash suppressors would screw with that. So I's say no for the time being.