I think I´ve seen a video where they picked up one LMG34 and just murdered everything
Though maybe that was fixed already, since it was quite a long time ago
Also, one can try to have a Brit teammate drop them LMGs via the HT commander
https://www.youtube.com/watch?v=7x0m0VE0MmE This one? Pretty funny! Dropped LMG34 got nerfed hard, now it's basically an LMG42 (so still pretty good).
BARs on Pathfinders are bad. The DPS increase is less than on other USF squads, they drop a lot, the range curve/fire on the move is a poor match. Use them behind other BAR squads for best results, or get them a real MG.
Just a side note- Pathfinders and JLI moving accuracy is really low, but their fire isn't slowed down. Switching that around may be a good gameplay indication to not use them while moving.