However based on watching the wild man that throws guns in the mud at the Military Arms Channel, the striker fired 320 easily bests the external hammer guns as far as ability to work when its real dirty, the glock and vp9 also does well. Yes no one throws their toys in the mud on purpose, so don't go there, however Shiites do happen.
When it comes to really thick mud, the striker system has an advantage over an external hammer. When it comes to water, the hammer system tends to be more reliable than the striker fired pistols. They each have their strengths and weaknesses...there are no super-guns.
