This would be a good change, but you can basically do that already if your discipline is maxed or fairly high and then run the scavenger perk. Your tripmines (and throwing knives) come back almost instantly with how much special ammo is laying around the maps. I can block off 2 doorways/ hallways and have the 30 seconds. Although, I would still rather have 2 tripmines than them lasting longer. Good idea