Actually, the action used on the 580 series rifles, is the 540 action. the 580 series was a budget bolt action rifle. The same action was used on on the 540X, 540XR. 540XR jr, 541T, 541X and the 541S. The 540XR has 2 large action screws, whereas the 541 series only has one action screw. I think (but am not sure), the 540X had one action screw as well. All of the rifles are very good shooters. The 541T, 541S and the 540XR all have adjustable triggers, whereas the 541X has a non adjustable trigger. Here again, I am not sure about the trigger of the 540X. I run a Junior Rifle club, and we have a number of the 540XR, 541T and 541X rifles. The one thing I have found about the 540 series rifles, is that the bullet does not stabilize well until there has been about 10 shots run through the barrel, at the beginning of a match.