Hello there. Just a few points off the top of my head:
- The combination of runes on your runesmiths is legal, so nothing to worry about there.
- purring a runesmith into the iron breakers might be a good call - granting them armour piercing attacks really improves their damage output.
- I'd look into getting an army standard bearer. They're absolutely worth their weight in gold (or gromril...) - even with LD9, we rail 1/6 of our LD checks - the BSB is really valuable for keeping our units fighting.
- Unless you really like the model, or want him for narrative reasons, I wouldn't take King Belegar. Like all the dwarf lord choices, he's really expensive for what he does, and unlike the normal dwarf lord, he isn't all that tanky (a king on shield bearers has a valuable role in taking on super tough characters, but Belegar isn't all that good at that either). For the price he is, you could get around 20 hammerers, which will scare the enemy much more. In terms of damage output, he's really not that great.
- As you've got a lot of artillery, you might like to look into getting a master engineer. He can really help them out, especially the organ guns.
- I'd give your quarrellers either great weapons or shields. Either is a valid choice, but it greatly improves their versatility. I'd probably give them shields, but that might just be me.
- I'd try and put the Groth 1 Eye banner on your hammerers. This will make most of your army stubborn, and so very difficult to shift indeed. It's an absolutely wonderful rune!
- I'd try and fit in some gyrocopters. They're really handy, and a bargain for the points. They're the only thing we have with much mobility, and so are well worth taking. Also, their damage potential is pretty significant.
- I think the unit of iron breakers is a bit small, personally. I'd suggest trying to make them bigger, or dropping them entirely and getting more hammerers/core models. If you give your Xbows shields, they become fairly resilient themselves, so the ironbreakers become a bit less useful, whilst the hammerers become more so, as you need at least one unit with serious damage potential. However, 15 ironbreakers, especially if they're stubborn, definitely have their uses, so it is just something to think about.
- I might be inclined to drop one organ gun, and get more iron drakes. The iron drakes are less dangerous point for point for shooting, but are much more flexible and much less vulnerable. I personally really like iron drakes. The use of the slowness runes on their banner is a very good idea - I like that a lot! However, as you're splashing out on the banner, you might as well make the unit a bigger one. I often use a unit of 20 iron drakes with 2 runes of slowness, and they always do very well indeed. They're numerous enough to soak up some damage, and can be a real threat on the countercharge.
Basically, I think this army could do with a few tweaks, but relatively minor ones. If it were me, I'd drop Belgar, and replace him with a BSB (probably with the Grungni rune, and any other runes to suit your personal choices), a gyrocopter, and then the odd extra model here or there.
I might be inclined to say your units are a bit small; I might be inclined to scrap the thunderers, and use the points to increase the size of both units of Xbows. However, I like big units, and smaller ones might suit you better.
It's just some assorted thoughts, but I do hope that they're helpful!