Which it does, as I've explained. I never offered up any houserules as an explanation of how you could make a sniper in Dark Heresy.
Matter of fact, let's go through it point by point.
SP, Bolt and Las training, Marksman, Dead Eye Shot (and it's upgrade, which i forget the name of), Mighty Shot, Crack Shot, Sprint...and i forget the name of the talent that Ignores Cover, but I know it exists. These are all available in the current set up.
New Talents (OW and newer): Stealth Sniper (makes it bloody impossible to find where you're shooting from), Versitile Shooter
Skills: Stealth (or Concealment/Silent Moves for old DH), Survival, Awareness, Operate: Aeronautica (Snipers should be versed in drop ops), Scholastic Lore: Tactica Imperialis, Tech Use (creative use of vox channels is a plus), Security, Athletics skills are a plus as well. The majority of these skills should be upgraded to at least +10.
Characteristics: BS 50+ (60 perferred), AGL 50+, PER 50+
What you have is a character who can get into position anywhere they need to and can make the shot from any range or angle they need to. They can even get accuracy bonuses out of some non-sniping weapons and good luck spotting them before, during or after their shot. They'll have ample time to get away when their target is down as well, partially due to their talents, partially due to careful planning, which is what a sniper should be all about.
Of course this isn't a starting character, but it's easy to play this type even before you've got all the necessary tricks. You do the job enough, it gets easier as you go. That's experience.