Clipping through walls to kill mechs

I can't tell if the mech is clipping through the wall or if weapons are splashing through the walls.  When a mech gets RIGHT up to a wall you can be on the opposite side of said wall, shoot at them, and kill them.  I haven't tried this specifically with all weapons but for sure the default Laser Rifle and Grenades.  

My guess is that it's the mech cliping through.  If you look closely you can actually see bits of the mech frame sticking through.  So people think they are being clever or tactical hiding in a corner or behind a wall.  When they get right against it I just blast them through the wall.  

Super cheesy and hopefully can be fixed; thanks!

Also... are grenades supposed to run through walls?  I notice the stupid laser drones do too.  Really feels lame that mines can go through walls.  Again you can get unsuspecting people so easily this way.  I'll even go behind a wall to safely toss a grenade (and the wall obscures it for a second) and zip around the corner for a quick kill.  Feels super cheap but works so well.  Would rather mines didn't go through walls.  

Thank you