I recently started playing Deathwatch and after our first session, it became apparent that it seems that wounding hordes is particularly difficult with standard bolt weapons (without specialized ammo). I am just trying to figure out if my group and I are doing the mathematics incorrectly because it seems that even the vaunted heavy bolter is not particularly impressive when it comes to wounding hordes. As of the rules in pg 359 of the Deathwatch rulebook, you have to do 15 points of damage to a horde after their armor and toughness.
Hormogaunt Horde (Magnitude 30, toughness 3, Armor 3)
Bolt Pistol: 1d10+9X, Pen 4, Tearing (I need to roll a 9 on two dice to wound)
Boltgun: 1d10+9x, Pen 4,Tearing (I need to roll a 9 on two dice to wound)
Heavy Bolter: 1d10+12, Pen 5 (I need to roll a 6 on two dice to wound)
Is this working as intended?