I just got Against All Odds from a rare engram, my first legendary heavy weapon. It is great in the Crucible. Unfortunately, it doesn't have any outstanding perks.

The barrel attachments all do different things, things that are not present in the descriptions for some reason. The linear compensator is kicks the guns recoil up by a noticeable degree while simultaneously reducing horizontal recoil/sway. Basically it kicks up the vertical recoil of the weapon while reducing random horizontal sway which is completely uncontrollable compared to vertical climb. For Light machine guns and auto rifles that have it, the best barrel is the field choke (especially on guns with naturally high stability like the Suros Regime). That barrel has minimal kick and minimal side to side sway while keeping the bullets fired in tight spreads so they don't veer off where you shot at. Honestly just avoid linear compensator if the same gun has field choke, as its the best barrel for lmg's/rifles, even better than smart drift control.

Yeah. That upgrade confuses me as well. It states three things. Two of which seem to contradict each other.