Basically it is a large size Heavy Autocannon. What they have in common:
- Both shoots a volley of projectiles with no charge-up delay and with the same projectile speed.
- Both provide sustained kinetic pressure, whereas Heavy Needler provides strong kinetic bursts.
- Per-projectile damage is mid-range compared to other kinetic weapons of the same size, neither high nor low. This tends to not only damage shields, but also slowly strip armors and hulls.
What is different:
- Mark IX Autocannon has faster turn rate: 10 vs 7. It does matter on Onslaught.
- Mark IX Autocannon shoots 4 projectiles per volley vs 3 for HAC.
- Mark IX Autocannon has much higher per-projectile damage: 200 vs 100, so higher armor stripping power and longer shield overload duration.
- So the per-volley shield damage is 1600 vs 600 (if all projectiles hit).
- Mark IX Autocannon has longer range: with ITU on capitals, that’s 1440 vs 1280, 160 more, so Mark IX will always fire at least one volley before HAC fires its first volley.
- Mark IX Autocannon has better accuracy and it shoots its 4 projectiles in a tighter time frame, so better effective DPS against small/moving targets.
- Mark IX Autocannon has a longer overall volley re-fire delay: 2.3 seconds vs 1.4, which is a drawback (but not as bad as with Heavy Needlers). I still consider this to be sustained fire, especially when shot at long range.
- Mark IX Autocannon delivers 348 DPS vs 214 (if all projectiles hit).
- Mark IX Autocannon has a 230 per-projectile flux cost, HAC has 100.
Considering Mark IX is 18 OP and HAC is 10, I would say we got a decent deal. You could reduce the per-projectile flux cost to, say, 220, but I suspect it would not really matter in the end. Hmm, and/or maybe raise the per-projectile flux cost of HAC to 110.
On Onslaught, my typical load-out has: 1 Mark IX Autocannon in the center
and 2 Heavy Autocannons in the front side. This never disappoints. Both gun types work well-enough together. This way the Mark IX provides superior kinetic front range (which I consider important on this ship) and good overall kinetic effectiveness.
On Conquest, my typical load-out has: Mark IX Autocannons in the front large ballistic slots on both sides,
and Heavy Autocannons in the next medium ballistic slots on both sides.
On Dominator I often use
either a pair of Mark IX Autocannons in large slots together with medium HE guns in the medium slots,
or a pair of Heavy Autocannons in the medium slots together with large HE guns in the large slots. Sometimes I mix 1 Mark IX Autocannon with another large gun,
and a least 1 Heavy Autocannon.
Same general approach on Legion as on Dominator.
(notice I did not mention using Heavy Needler on any of those ships)
My points being,
- overall Mark IX and HAC serve the same purpose in a similar way
- Mark IX has clear performance advantages compared to HAC, and some downsides too
- needlers are entirely different beasts.
