But snipers don't kill by inflicting damage, they kill by inflicting a kill critical on an infantry hit, don't they? I'm not sure how trivial it would be to remove the kill crit then give the sniper rifle damage, but at the very least, it would be more complex than solely adjusting the cover multipliers.
You are right, I did forget about that, and I can't claim to know about just what's possible with making crits. Maybe a "Cause 40 damage critical on a penetrating hit" is simple to make, maybe it's not.
I am leading to toward the former in my assumptions after a quick glance in the attribute editor though, since I believe the Ostheer sniper's Incendiary Shot ability's weapon section in the attribute editor causes 50 damage on a penetrating hit against light vehicles, so it may be capable to adapt the concept against infantry along with adding a requirement that the target be in heavy cover...but the latter part is definitely a bit more beyond me since I don't actually know of any abilities that anything like do that.