The following is a walkthrough of the Gun Runner mission in Grand Theft Auto: Vice City.
Walkthrough[]
When the mission starts, quickly get in to the nearby Patriot parked in Phil's Place, then drive towards the targets. This mission introduces you to the Remote Grenades, which is spawned near the entrance. There are four trucks to destroy: two in Little Haiti and two in Downtown.
There are many ways to get them. You could try out the Detonator Grenades or use any other weapons, like the Sniper Rifle. The weapons you have to collect are inside the box that has to be destroyed at the back of the truck. You have to pick up these weapons even if it meant replacing your current ones.
When you collected two guns, the Mexicans will send back-up using Faggio scooters driven by the enemy with Uzi submachine guns. The other two trucks will drive more aggressively. Killing these enemies will earn you a $100 bonus. They will endlessly come so you can't hang around. Be careful of the Waltons, they will try to run you over.
The mission is complete after you have collected all the guns and destroyed the trucks.
Alternate method[]
Although Phil asked Tommy to kill the dealer, is not really necessary to kill them to complete the mission: you just need to get the guns and destroy the Waltons. If you want to finish the mission with fewer dead, just shoot the Waltons until they start to catch fire, allowing time for the traffickers deviate from them before explode.
If you want to do it, let it get the guns finally avoiding traffickers bikes, which will make the task much easier and faster.