Stone Warriors (Spears)
At the beginning of the level a Stone Warriors will come flying toward Lara. While in the air they are slow and Lara can shoot them with the M16 from afar.
On the PlayStation you could get rid of them before they came to life, by shooting grenades at them.
This doesn't work on the PC, however you can predamage them so they only need one shot after coming to life. Only the spear gun can do that. Shooting them three times with the grenade launcher while still stoned will cause the system to crash.