Ok, I'm dumb. Because the barrel becomes invisible, I thought that it didn't block the bullets (the first time I tried, they shot me anyway, while holding the barrel, but I guess I just held it at the wrong angle). I've managed to beat the game, it was fun. I like the surprise jail room :D
Funny thing is that I didn't get that barrels can't pass through doors. :D I was moving with the initial big barrel all the time. After some deaths, I realized that this is not the idea. :D
Good job. :)