The HB is actually (marginally) superior at killing marine-types in the TT than the autocannon is. (1/3 chance vs. 5/18 chance if fired at BS3.) Shorter range though IIRC,
Those are average number of kills, not probabilities of scoring a kill, but that's a detail.
But indeed, you're right. My bad.
Having nothing better to do with an hour, I did the math, and the HB performs better (either significantly or slightly) against all forms of infantry than does the AC. In fact the HB is the best heavy weapon, period, against all forms of infantry (except possibly a frag missile against tightly-packed blobs) with the exception of the plasma cannon. The AC is a light-vehicle/Monstrous Critter killer and is mediocre against infantry.
In fact, the autocannon does not perform significantly better against infantry than do lasguns, leaving range out of the equation (which is admittedly a big, big, omission):
Consider: Two Guardsmen (= 2 lasguns) becomes 1 autocannon heavy weapons team in TT (you exchance 2 GM for an HWT, in other words). Assuming that range is short, the two lasgun guys get 4 shots vs. the HWT's 2.
If shooting at marines (T4 Sv3+) with BS3, the math looks like this:
Lasguns: 1/2 x 1/3 x 1/3 = 1/18 x 4 = 4/18 = 2/9 = 0.22. If you FRFSRF that, it becomes 1/18 x 6 = 1/3 = 0.33
Autocannon: 1/2 x 5/6 x 1/3 = 5/36 x 2 = 10/36 = 5/18 = 0.28.
In other words, at short range (admittedly a big factor), lasguns (or rather the two lasguns that you would need to get rid of to get an autocannon) are only marginally worse than autocannons against heavy infantry, and superior given FRFSRF.
An HB on the other hand gives you
1/2 x 2/3 x 1/3 = 2/18 = 1/9 x 3 = 3/9 = 1/3 = 0.33.
That is, the HB is 150% as good as the lasguns in normal circumstances and identical with them given FRFSRF.
OK. This has been a long digression . From which I extract two things. 1) in TT, if you are planning on going up against infantry of any sort and not vehicles or Monstrous Critters, ALWAYS take the heavy bolter over the autocannon. 2) FFG is not modelling the TT weapons effectively at all.
Edited by bogi_khaosa, 15 March 2014 - 08:42 AM.