I ended up having to knife three of the battle mechs as they were so stingey with the ammo in the final levels, but I think I must have missed picking up the Gehenna somewhere, as there were ammo drops for it but I only found the gun in the final level. Polish game needs more polish, but it is actually far closer to what you would expect if you were told that the Redneck Rampage guys were going to make a new Wolfenstein game back in 1999.