This Seeking Tech guide will show you how to get the Just Because trophy and achievement in the Master Collection version of Metal Gear Solid 3: Snake Eater.
This will unlock when you “blow up a munitions shed with TNT.”
The first opportunity to do so is at Bolshaya Past Base. Take care of the guards there first, and then head to the shed located in the northeast of the map. Inside there, you should find some TNT.
Plant the TNT in the shed and then head outside to create some distance. You can then detonate the bomb to unlock the trophy.
Check out the video below if you need additional help: