The Punk Weapons are a new bunch of weapons released at the end of March 2011. They differ from all weapon sets released so far because it includes the new weapon type the Grenade Launcher, along with complete new kinds of Pistols and Shotguns.
The second lore delivered by the Punk Heroes 2 was even more extensive and featured a full range of weapon types, like Sub-machine Shotgun, Shotgun with Grenade Launcher or huge demolishing Rocket Launchers. These are the last re-skins (except Brute Puncher/Titan's Thunder and Nailer/Leadstorm) to known being created and released.
The Grenade Launchers featured in this release were most likely included due to popular demand from the community after a forum post in the Suggestions by SufferBaron. In this post the weapon was intended as a means for soldiers to defend themselves from Tanks. Despite the original idea the weapons now found in game are considdered Anti-Infantry by some players rather than Anti-Vehicle. They were also designed to be barrel brake models where the barrel has to be broken and a new round inserted rather than the six-shooter revolver style that made it to the game.