I'm better with a Brute Shot than a Grenade Launcher except when it comes to the lower difficulties of Reach at the start of Tip of the Spear. Most heavy weapons are not my strong points in the Reach Arsenal. Pistols, magnum, precision weapons, and rifles are what I lean to.
Jun was also always be a better sniper than me.
Occasionally AI will do things that work in my favor like inexplicably driving a Wraith off a cliff at the second AA gun on Tip of the Spear. Or a Brute with a Hammer over jumps and falls off the cliff in Overlook.