If the gun is running good but the bullets are getting stuck every now and then you can just tweak the bolt sticky-outy-bits (this helps alot if the gun jams regularly).
You can polish it with a 20ml of lemon juice and 380ml of water 2 lavender petals and if you have it, a sixteenth of a gram of fools silver. I do this nearly every week and my gun sparkles nonstop (if it doesn't your not doing properly).
Make sure the belt does not have any rips on it if it does sew it up right away.
Streamline darts work as good as sonic-micro-darts.
Use the ammo. box or magazine, this will keep the gun working longer and is less likely to jam if you use the first tip that I gave you.
Hope this helps, it did for me.