In a real gun, the bullet actually travels down another "barrel" inside the silencer. This minor variation will distort accuracy and reduce FPS by a little. Besides, in a suppressed weapon you should be using subsonic rounds so your velocity will be reduced anyways.

Airsoft supressor and Real steel supressor work on the same principle. Only in airsoft, we don't deal with hot gas and high pressure. So we use foam insted of steel chambers inside the supressor. Both work on the same principle though. Reducing the air pressure at the mussle, wich make most of the noise of the report. The other noise source is the bullet super sonic bang. Wich is eliminated with subsonic rounds.

If you want to see how a real supressor is built, look it up on the internet, I once found a nice cut away of a MP5SD supressor.

The air currents down the barrel (real steel and airsoft) are changed once the barrel changes to open air (unsuppressed) or changes to foam and then from foam to air. I don't know how to calculate, but the fluid dynamics from 2 medium transitions do add a small effect on fps and direction depending on if the air propelling the BB or bullet is twisting or passing by on one side.
A tiny defect can allow air to pass through on one side of the projectile causing a low pressure on that point...it's seriously a highly variable system.

If I'm not mistaken, the main report of the gun is heard because the air goes from being pressurized and confined to the barrel to an unconfined space where it rapidly loses pressure.

Basically, building a pressure wave that travel a certain distance.... wich we call sound.

If that pressure wave is dissipated, the sound produced is less audible.

Well i took my ak outside and gave 3 round bursts at a pole without the silencer and 2 out of 3 bbs hit the pole. But when i put the silencer on 1 out of 3 bbs hit the pole so i guess it has something to do with the bbs hiting the inside of the silencer.

as for muffling the noise from the mechbox i couldnt really tell the blowback on the ak74mn is pretty luod everytime i shoot i hear a clack clack clack.

I had an AUG with foam stuffed around the mechbox, and a First Factory OPS silencer. I lost 20 fps with the silencer on, and I used that silencer on the AUG, MP5K and G3/SG1. All guns lost 20 fps.

That AUG was so quiet, I could tag a guy in the bush at less than 20 feet, and his buddies had no idea where is came from.

I've shot people from 20ft away with my Mode-2 suppressor and they could tell where the shot came from. My gear box is quite also.

Personally i think that it does work (though it's hard to tell sometimes becuase AEG's are already have a medium tone). But I just did a few test shots with my CQBR, forst with just the standard M4 flash hider, then with my ICS QD KAC silencer, then again with just the flash hider then a Madbull Novezke KX3, and repeated the cycle then mixed it up a bit. And yes i did notice that the suppressor does soften the sound a bit (IMO by about 35-40%) and the KX3 increases the sound by about the same. I think that it is a more dramatic sound diffrence in shorter barreled guns. Also i bet that this would work wonders on a 'classic' gun much more so than on an AEG.

I had a halo gemtech on my ptw, not much difference up close, but from far away when i shoot, i've been told that they can't tell where it's coming from, so it's a pretty nice effect.