These were the "big guns" of the MRF. This one has a 40mm gun in the front turret. There were more incarnations of this boat than any of the others. The later models borrowed turrets directly from their dry land counterparts with guns as big as the 105mm howitzer. A canister round (like a giant shotgun shell) from 105 could cut a big hole in the vegetation and whatever tried to hide behind it.

That's a 20mm sticking out of the top turret.

This one is riding a little low in the water.

The VC's view of a Mike boat.