The shattering into pieces part can be done by destroying the crate on collision with the bullet and creating crate bits at its former position.
Overall you need to store the bullets angle on impact and just apply it +/- any random angle offset (to get a cone effect) to newly spawned crate pieces, which should have bullet behaviour. You can also randomly set their speed and accceleration (negative to slow down!) to give the impression some are heavier and some are lighter.
Here's an example. The simple square cratebits sprites could be changed for actual fragments of your crate sprite, you could do multiple frames for the crate bits, disable the animation by setting the animation speed to 0, and upon creation assigning a random frame.
https://www.dropbox.com/s/3vluoo10v8ncp ... .capx?dl=1
Thank you so damn much Pulstar! [Sorry for the minor swear ]
You've really helped me and I feel so damn awful for not replying after such a long time, here is the end result:
Also I will be sure to add you onto the wall of credits <img src="{SMILIES_PATH}/icon_e_smile.gif" alt=":)" title="Smile">, You deserve a something.