Hi.

I feel a bit foolish for asking but just wanted to make sure I haven't missed anything - is it within the rules to aim before firing automatic fire? I haven't been able to find anything against it so if it's not the case please provide a reference.

Thank you in advance.

Not in the same round. Full auto is a full round action. Aiming takes a half action. So you can't aim and do Full auto at the same time.
It looks like you can first spend a round aiming and then use Full Auto though. For a total of +40 to hit (which is rather sick).

That's what I thought then, excellent. Thank you for your time.

Although don't forget if you do anything (like dodge) between aiming and shooting, you lose the aim.