This is a triumph that isn't going to be completed with great ease in the current mindset of Destiny 2's crucible in regards to Grenade Launchers of both kinds... as this Triumph, which is required for "The Mountaintop" Grenade Launcher, will require 3 things: A whole load of luck, A whole load of patience and be willing to camp for heavy. Here's why I say this: Single shot grenade launchers cannot reliably one shot UNLESS you're using Militia's Birthright with Proximity or Spike Grenades, and that is the only Random Roll Single Shot Grenade Launcher in Destiny 2 (as of this post) or Fighting Lion. Here's another reason... you only get 2 shots with a Single Shot Grenade Launcher UNLESS you have Fighting Lion which gets 9 shots, which shows a lot of bias towards that Exotic but also means it's the only SIngle Shot capable of "Calculated Trajectory" medals without relying on Special Ammo RNG or Heavy Ammo for Drum Barrel Grenade Launchers. Heavy Grenade Launchers work well for this, but good luck getting ammo because (as of this post) it only spawns in one location per match... which means people are likely to be camping for the Heavy Ammo, just so they can have a chance of completing this Triumph. Heavy should be based on a random rotation of 2 or 3 spawn locations for each given map to prevent this... Special ammo should also be a guaranteed drop from Guardian kills, regardless of them using a Special Weapon or not, as I have been left with 2 kills and no special ammo before, only to get killed trying to kill another guardian to have a chance of getting some special. As for the Single shots, they should be treated equally in terms of ammo reserves. Why should fighting lion be the only one to get 9 shots? The other special weapons, regardless of quality, always get 2 shots each. The only way i can see this triumph being completed with some consistency is waiting for Mayhem and grinding that, and/or waiting for the "Lake of Shadows" strike to become available for grinding as a nightfall. Either way guys, good luck completing it until Bungie alters some things (which may never happen)