Trying to shoot through 21 2-liter soda bottles with a Browning BAR ShortTrac .308

Here is an attempt to shoot a .308 rifle bullet through 21 2-liter soda bottles lined up in a row. As you will see, the bullets would not go through more than 4-6 bottles each time we tried it. We also did some other bottle shooting and slow motion video. You'll see that one of the bullets remained lodged inside one of the bottles, probably after hitting the wood plank first. Our rifle was a Browning BAR ShortTrac .308 semi-auto 5-shot.