Sentrys also drop fusion cores, 2 usually. A tough fight, even in power armor. I just strategically lay landmines and kite them, they move quickly so you will need to sprint to do it successfully. When they get to a low enough health they shutdown for a sec and their fusion core covers open up on their back which is their vulnerability. Then its hammertime, job done. Kite-ing is easily the the best way to abuse the mechanics of AI in any game, even some dumb human players will fall for it. For those who dont know how it works its basically using line of sight to make AI take a path you want, like flying a kite. Do it right and you will take minimal damage while the dumb ass runs over all your mines. Works well in other games that have damage over time mechanics. Apply DOT, get out of LOS run around, back in LOS to apply DOT again, rinse and repeat. Can also kite to a choke point like a door way, have your crossairs at head height...easy. Some AI is smarter than that in certain situations.