As far as I know, some suppressors/silencers are aesthetic and some function to reduce the report of the gun. The former usually are just a tube while the latter usually have foam inserts.
Most people that add an attachment to the gun (whether it be a suppressor or something else) use it as a barrel extension so they can add a longer inner barrel. In that case, it actually helps to improve accuracy. However, I'm not sure about the effect on accuracy when just adding an attachment without a longer inner barrel. Assuming that the attachment is straight and doesn't obstruct the flight path of the bb, I'd imagine little to no effect. Totally a guess, someone please correct me if I'm wrong.
Originally Posted by OptimusPrime
I could never stop going to WalMart. Its the only place I can get good airsoft guns.