>>302720823
Once they get close they stop shooting, turn off the shield and do a really slow headcrab jump. They don't put the shield back up or start shooting again unless you open the distance. Bait them around a corner or just rush them if you're in a hurry. They're too early in the game yeah but they just want you to play differently than most non boss enemies. Kind of like how you learn not to shoot the bomb drones, just wait til they reach you and run when they pause to explode.