I had always assumed it to be built on a beretta. I have seen an rpf memeber do the police guns, but as far as I have seen, no one has done the mangalore pistols. I can't even find a decent screen caps of one online. :confused
It's definately a 92 F Beretta. There's a picture in the official strategy guide from the old play station video game that shows a hero version, and you can clearly see not not just the trigger, but part of the guard as well.
As it turns out I've got a set of plans drawn up to try and put one together next month.