I think i he crouches and goes around the rail so he doesnt fall, but thats my guess
You can watch the Glitchless wr by glitchyboi to see how he does it, ill leave it here:
U have to place the wheel in a spot, then crouch jump (crouch + jump + crouch) on the wheel, go as far as you can, and after u do that, run back and u should be able to clip through.
the easiest way i found was using the car wheel near the neighbors car to clip through it (U NEED TO USE 23 FPS) and u have to place it in a specific place for it to work. u can watch the WR run for that.
le moyen le plus simple que j'ai trouvé était d'utiliser la roue de la voiture près de la voiture du voisin pour la traverser (vous DEVEZ UTILISER 23 FPS) et vous devez la placer à un endroit spécifique pour que cela fonctionne. vous pouvez regarder la course WR pour cela. (i used google translate for this so idk if its correct or not)
Bigboi make me verifier I know the game best (I'm muscă)
if this is any% then u can get the gun in a3 in under 15 secs imo