Algodoo

You've got some big trouble there!
First of all, that's too much strength for the bullet! If you use so much Nm on the spring, the bullet will try to go a little bit upwards or downwards, and it'll get jammed where the barrel starts.
You're using too little density on the shell and the part of the bolt that touches the shell. use even more! (I use 200-500 kg/m2, although it may sound massive)
Also the bolt movement is too much, and this will reduce your firerate. try to test values on the bolt spring to make it move just the necessary amount.
And if it still doesn't work, try 300 Hz. but you should try to make it work by any means before doing this, because that mag is quite big and it'd lag to a lot of people.

Oh, and one thing more: tweak the extraction of the empty shells because they always fall into the system!

Thanks for helping. I'll do my best about it.
By the way. Do you have any skype accounts or anything like this. I think you're probably the best "weapon" desinger here.

Yeah, I've got skype, but i just use the chat. Tell me yours and I'll add you

If you think I'm the best, then you're forgetting ngphil and yuras12!

Okay then.
It's not because the design itself. It's about some kind of theory. I actually don't know how this algodoo engine works. Thanks for help again.
Of coures, there's my skype: notarget137 (obviously, duh?)