Most primers are very hard on the euro ammo (wolf/S&B)
I know once I accidently left out the disconnector and I got 2 double taps and then a FTF.
The round had a firing pin mark on the primer but didn't fire.
I have read that if you file the firing pin to a point that if will go full auto without a disconnector. This is because the sharper point of the firing pin puts more pressure on a smaller area.
Basically instead of 1mm impact mark, you would have a 1/2 mm impact mark.