User blog comment:Brothertim/FMJ in SMG: tips?/@comment-1079585-20100519160742

Silencers do not reduce penetration. The only way the silencer could negatively effect your ability to kill through a surface is if the target is at a range where you would be doing more damage without the silencer, but with SMGs that is a very narrow range interval and it still isn't much of a drawback.