Nobody, that's who.
If you'd like to add a new, giant chain gun tank to your arsenal, then Forge World has what you're looking for. They're taking orders for their new Legion Sicaran Punisher Assault Tank over in their webshop now.
From the announcement:
The Punisher-type Sicaran variant came into general use amongst the various Space Marine Legions in the final days of the Great Crusade, however the punisher rotary cannon it mounts has a far older history. Originally mounted on the now rare Cerberus pattern main battle tanks, the punisher had established a reputation as a deadly tool in the eradication of massed conscript infantry or hordes of swarming xenos creatures, limited only by its relatively short range and prodigious appetite for munitions. Married to the Sicaran hull, where the impressive speed of that vehicle effectively negated the short range of the weapon, and the complex feed assemblies developed as part of the various Terran accelerator cannon, the punisher is once again in widespread use among the Legions, though now it is employed against the very warriors it was intended to protect.