In most cases, no. Jackhammers are by far the Fencer's most valuable melee weapon and much more versatile. But against red ants on Inferno, absolutely, or in very close quarters like an underground tunnel. It takes about 2.5-3 seconds for a full charge and it dishes out 12,000 damage, the highest of any striker or piercer, and I think the highest of all the Fencer's weapons, discounting the laser guided rockets. I'm fairly certain it's the only thing he has that can down those red buggers in one hit. You're also protected from 90% of any damage taken while attacking. Only the Vulcan ZD and Finest Hammer offer that much defense.
I wouldnt use the vulcan zd, the explosion is just too small, and even the previous model with a slightly bigger blast can be hard to use. I used dual vulcans in the "trap" stage and it didnt go as good as I imagined.
Finest hammer destroys buildings and hits lots of enemies, id certainly pick it over the vulcan hammer except maybe for stages where the majority of enemies are hectors of something strong yet small in numbers.
The jackhammer is very good but i kinda find miself using the blasthole spears much more, maybe its because the jack hammer wont let you cancel anything into it or out of. It feels like its good for pairing with guns to take down enemies that close in tough. --- http://k7sin.forumfree.it/
That's why it's so good against red ants, they get right up in your face and practically beg to get knocked out of the park. The weapon almost seems designed to combat them, as their hp is either 11 or 12k on Inferno, I tested it a few weeks ago. So it does just enough damage. It's the only weapon that can take them in one hit, and what's more - several in one hit. Air raids and ridiculous measures aside of course, like Gungnir, Monster-S, Leviathan etc.
You may want to try dual wielding them for successive hits one after the other. I prefer zipping in for a quick hit and backing out with the Javelin before I get surrounded. That's another thing I love, is that you can charge the Vulcan while catapult cancelling so it's ready when you need it. It's also great for closing tunnel exits quickly. If I were going to dual wield though, I'd go pure melee and equip the Javelin + Jackhammer as my secondaries. The Vulcan is a bit overkill for ordinary ants and spiders.
I have to say I _LOVE_ the JackHammer. I'm using the M3 model as I have nothing higher. Dash up to a Hector and bash them in the foot (or jump high to "get all up in their grill"). Repeatedly boost up into their air firing the hammer to take out the ants on the ground below... a quality weapon.