The Gulag - Trinity Squad Beyond the Gulag Base Camp (Part 2)

Once those two are dead, catch your breath before moving out from cover and starting up the hill. When you do, a short cutscene introduces the next group of enemies: 2 masked men with rifles and their heavily armored leader. There's also a fourth guy with a knife and anger-management issues, who doesn't appear in the cutscene.

When you regain control, Lara is crouching behind a small, green barrier. There's more rifle ammo on your left if you need it (circled above), also empty cans that you can use to craft shrapnel grenades.

To recap, press Interact to pick up a can. Hold RB/Middle Mouse to craft a grenade—provided you have magnesite in your inventory—and then hold LT/Right Mouse, move the right stick or mouse to aim, and press RT/Left Mouse to throw the grenade. A grenade should take care of one of the masked enemies. Or, if you throw it at the main guy, it will destroy some of his armor, making him easier to kill.

Poison arrows also work well on these guys since armor does not protect against poison.

In any case, you'll need to keep moving, since these enemies pursue Lara relentlessly and throw grenades, so any cover you find will not last long. If you run back down the hill and hide, you can buy a few precious seconds to heal before the enemies reach you.

The wacko with the knife will probably come first. Shoot him as he approaches. Or, if you've unlocked the Dodge Counter skill, wait for him to charge at you, press B/C to dodge, and then finish him with a melee attack by pressing Y/F when you see the button prompt. (Sorry no screenshots yet.)

The others will soon follow, but they tend to stay behind cover and try to snipe at you, giving you the opportunity to shoot back. Again, if anyone throws a grenade, move to another safe spot before it explodes.

The guy with the armor puts up quite a fight. Use a poison arrow if you have one. Otherwise chip away at his armor with the rifle until you finally hit flesh and he goes down.