Like someone else mentioned, MCH just does no damage. The first fix should be to up its raw potencies to be sort of like red mage. Red Mage doesn't bring a lot of utility, but just one or two neat little things. Machinist in the same way just with lower dps. The hot shot buff was nice and all, but it was nothing more than a Band-Aid on a broken rib.

Looking at the numbers I feel that all three shots(both heated and unheated) need to be bumped up a little bit.

For reference these numbers do not include ammo, but do include proc bonuses and go unheated/heated:

Split is 160/190. This should be brought up to 210ish/240ish.

Slug is 200/230. To follow the jumping change it should be 250ish/300ish.

Clean is 240/270. Again to follow the jump it should be 300ish/330ish.

I love the job, but its payout for effort is abysmal and it really needs to be buffed up to stand toe to toe with other "steady" dps jobs like BLM and RDM.

To those who will say these numbers are too high:
Look at how often RDM is throwing around 300 potency abilities. Its every other spell no matter what. If you think this too much than red mage is too much.
Then for turrets is they're more utility than actual dps. MCH is the third and final job that inflicts a vul up to all damage(BRD and NIN being the other two) and then the damage nuke ability.

That's just my two sense. I enjoy machinist and I liked how you had to line everything up in a methodical fashion to unleash a burst. Sadly this burst is cactus piss to pretty much everything else.