Ships & Modules

NPC's have tank too, and angles in particular are strong against EM/therm

You are hitting for way more on sanshas because you are hitting their resistance holes.

First, most obvious and therefore hopefully least likely consideration...
The Nav'poc of course has the range bonus while the 'geddon doesn't. If you're used to engaging targets at 50km with the Nav'poc and try the same with the 'geddon you'll suffer a significant loss of DPS (and volley) through falloff.

More likely (though given mission rats have set orbits, still not all that likely) is that the range bonus on the Nav'poc enables you to engage further out and therefore tracking has less of an impact on the Nav'poc (rather than the Nav'poc having better tracking).

Of course the 'geddon has fewer turrets (so the volley will be lower despite the ROF bonus and huge drone bay which should yield higher DPS) but that certainly shouldn't be sufficient to cut your volley in half.

Edit:
Noting your reply, the 'geddon will suffer far more significantly with cap issues due to its smaller cap and higher gun drain, in terms of finishing missions solo that will certainly make it feel a lot more difficult, though again it shouldn't hurt your damage so much assuming equivalent resists...etc.

At the very least, it works as a support ship, which is all it was ever intended to be.

I'll try that, thanks.

Given my 5M sp in gunnery and damn near perfect (battleship) support skills, I think the drones must be the issue.

For reference its pretty good for shaving dickstars and camping dudes in station while you reinforce it.

And then there is the 1300DPS shield fit rail domi, but lets not get into that

@OP - it took me losing a pair of well fit max skilled Navy Geddons; one to mis timed aggro (damn drones) one to scrams (damn Gallente) before I got wise to the fact that as good a boat as the Navy Geddon is its bonuses don't lend itself to solo L4 missions easily. The Navy Apoc is a much better mission boat than the Navy Geddon is becuase of its bonuses, cap, and PG. In many ways its just like how the t1 Apoc is superior to the t1 Geddon. Also there is a big difference between Paper DPS and applied DPS and in PVE situations the Navy Apoc puts out more applied DPS than the Navy Geddon does.

However, if I'm going on a structure shoot or some PVP action, I'll take a Navy Geddon over the Apoc becuase the bonuses work out better for the Geddon as a PVP face melter. And you get a utility slot for the all important Nuet ~or~ Remote Repper without the DPS sacrifice.

TL;DR One is a Circular Saw, one is a Chain Saw. Both are tools with specific purposes.

Implants don't fix the horribly exaggerated range and that's the ship's biggest problem. 21KM optimal (with 3 scripts in) is quite low and you will find a ton of rats in Amarr missions that are well beyond that range. As a result, you'll be using scorch almost all the time, and you'll probably need to switch to bouncers or another longer-range drone so that your sentries are usable in those missions as well. That cuts the DPS down quite a bit. The other real problem I see is the lack of a prop mod. Personally, I rarely fly a mission boat without one, as there are just too many missions where you need to move from point A to B and there's no point killing the rats quickly if you're going to spend the next 5 minutes slowboating to the next gate.

Honestly, I'd go with a Navy Apoc for missions over the Navy Geddon, simply because the range bonus lets you use multifreq crystals more often in the Apoc. The other option is go to with something that fits beams like the Nightmare or Paladin. Save the Geddon and its variants for PVP.

QFT