Its damn near impossible to play Destiny like we do Call Of Duty, as Mocubitz stated there are so many factors that play into a death. Any sort of restrictions placed will give you a really really big disadvantage and there is no way to combat that. I understand the medals are meant to show gun skill, but for destiny you can't just use your primary. There are so many factors in a death, classes, abilities, supers, special ammo, and heavy ammo. The nice thing about super abilities and heavy ammo is that you don't have access to them all the time. All supers are a one time use or they have a timer, one used up you gotta go earn it again, For heavy ammo that only spawns a few times a game and doesn't give a whole lot of ammo. Also if you die with heavy ammo you lose it.