DOOM 3: BFG Edition
59 Achievements
50-60h
Boomtastic
Blow up 50 barrels in the DOOM 3, RoE, or Lost Mission campaigns
12.4%
How to unlock the Boomtastic achievement in DOOM 3: BFG Edition - Definitive Guide
Just save while targeting one of them, shoot both and then reload the save. Do it 25 times and the achievement is yours.
You can save when you explode 10 barrels (after your reload the save) just for precaution.
Don't exit the game while doing this.
Note: This trophy is cumulative.
The barrels are the red barrels that have "Flammable" written on them. You just have to shoot them and they'll explode. There are hundreds of them in the Doom 3 campaign alone, just shoot all the ones you come across and you'll get the trophy in no time.
This is completely self-explanatory. Any time you see a red or yellow explosive barrel, just shoot it a couple times with your pistol (so you don’t use more precious ammo types) and let it blow; just make sure you are far enough away from it when it does.
This achievement should be cumulative across the game(s). Just make sure you blow up all the barrels you see and you shouldn't have a problem. It's possible to find an area with 3-4 barrels, save, shoot them all, load, and repeat the process until the achievement unlocks, but this will likely come with regular progression without sitting through the extra loading screens.