finding the panda and submit a high score

Hi,

I'm a noob when it comes to shooter games. So this might be very noobish questions..

First one is, why are not every weapon able to break barrels. The panda is hiding in a random barrel right?

The second question is that I have posted my score more than once but still didn't unlock the achievement. Any tips?

found out the panda's were in Crates, not in barrels. Now I only have the submit a score to the leaderboards achievement left.