Knowing the location of the free M-16 is one of the most useful pieces of knowledge in Grand Theft Auto 3. It’s second in power only to the rocket launcher and is more than handy to have at your disposal with its target sight.
Finding it is not easy and requires a little skill. First you need to head to the project yard on Staunton Island, as shown in the map on this page.
To the left of the project yard entrance are some steps which are to the right of the underground car park. Head up the steps, turn left and use the ledge in front of you to jump up onto the raised area to your left.
Once up there, taking a running jump over the gap to your right and with a little practice you’ll reach the other side. Head down the ramp, turn left back on yourself and there it is – a free M-16 which will re-spawn saving your valuable cash and provding some serious firepower to get you through the more challenging missions.