How to pick a gun safe?

Alright I need a little help here. I have an old gun safe that I have misplaced the key for. I don't have any guns in it but a bit of other things and I'd like to be able to get them out. I thought it would be more interesting to pick the lock instead of paying to get it opened.

I'm not exactly sure what the lock type is, but I can give a description. It isn't a lever handled safe nor an electronic one. It has a key that when inserted into the lock presses these small pegs inside. The key is a circle. The key is turned when pushed all the way in and that opens the safe. Is their any way to pick it without doing damage to it?

I had a timer that would shut an electrical device off over time. It had a similar lock only with one peg to push in. I could push it in with a paperclip to open it.

Anyways anyone know of anyway I could learn to pick it?