RAWmonger |
You should be able to, although it says "A larger version of the wrist launcher," but it does not say "this otherwise functions as a wrist launcher," which is the key phrase in pathfinder for stuff like this.
It's clear you can still conceal it under your clothing, since that's the whole point of a wrist launcher, no matter the size, but you may not get the "After firing, the wearer can attempt a Sleight of Hand check opposed by opponents’ Perception checks to keep the wrist launcher concealed."
Personally I'd say you get it, since if you don't carry over those rules for the wrist launcher, there's no reason you should carry over the reloading rules from the same text... which means there would be literally no written rules for reloading the heavy wrist launcher.