Luger Runaway
 

I just got my barrel replaced and was not previously able to test fire the pistol successfully. Now with the new barrel installed I've found that when you **** the toggle and let it go it snaps and lets the firing pin go. I was told maybe take a look at the firing pin. I was actually wondering that if I had changed the recoil spin and it was too strong if it could cause the toggle to prematurely fire when its released? I have a taken the liberty of getting ahold of the trigger bar spring and the safety bar since they are both loose. BTW this is a shorter with only the frame and upper receiver matching. I can say most of it besides these two pieces are all mismatched. Any help would be appreciated cuz I need to get this working so I can sell it and get my money back out of it to get a wartime luger

Its sear does not set. Since the first portion of the upper's motion, when fired, is when the interface occurs, the recoil spring is less likely a culprit than the sear (trigger bar) spring. If it's loose, it would function as you describe, so install that spring and see how it works afterward. Should eliminate the popppity-pop-pop-pop...