By observing the best runs that use this technique It is very tempting to do the same, this sometimes prompts people who start the "Gun Range" speedrun to sacrifice the grenade intended for the 2nd room to quickly pass the 1st room. This penalizes, a tip, if you want to use 1 grenade during your race, it is better to use it in the 2nd room than the first. It is faster to eliminate all clibles without grenades in room 1 than in room 2.
If you want to have 2 grenades during your run, here is some advice that can help you :
Starting placement : There is no 100% precise placement, the most important is that you are sticking to the wooden wall, and that the grenades are accessible.
Throw the 1st grenade :
The area surrounded by purple is the place to aim. On the demo_viewer version, it is very easy to recognize a bad grenade throw. It is only sound, if you hear it hit the wall twice it means that your grenade is thrown badly. If you hear him hit the wall once it means that your grenade is thrown correctly. On the current version it is possible that the grenade hits the wall twice and can be good, but on the current version it is the timming and the recovery of the 2nd grenade which is difficult.
Seize the 2nd grenade : For the gesture itself, the only secret is the training. Your hands will take the reflex gradually. The "Use or Pick up" key must be a mouse key, not a keyboard key. Example: MOUSE 4 To retrieve the grenade without taking an AK or M4A4 instead, you must press the "MOUSE 4" button when your sight is in the grenade box. The more you go to the left, the more the probability of getting a grenade increases.On the demo-viewer version, the movement should not be extra lively at the risk of losing the grenade because the game takes it away from you. On the current version it is the opposite, the movement must be extra lively.
Last step, get to the starting line before the grenade explodes : Facing the wall, go only to the right and a few ms later you advance while keeping the key (D) held. In front of the door you release the button (D). But again, it is only a matter of training.
Failure situation : I explained how to tell if the grenade throw is good. But how do you know if the timing is respected. There are still 1 possible situations without counting the wrong grenade throw on the demo_viewer version :
If the 2 "Yellow" and "Blue" targets (or one of the 2 targets) survived with a small hit point : AK47 was not taken in time. If the "Yellow" target survived with all of its life points : slightly too slow (At the start of the course, the targets have a short invincibility time, the lower left target has more invincibility time than the 2 other targets).
For the Current version, it is not necessary to take the AK-47 but it is preferable that the 1st grenade is aimed at the bottom of the purple square in the previous image. But if you don't want to take any chances, take the main weapon during the explosion of the first grenade. (I must point out that I am not English and all text has been translated, sorry for the mistakes) I wish you good luck.