Firing pin protrusion is not an issue with the rifle I am using.
I too have blasted away many rounds of the Yugo surplus both old and new and in the same rifle. All of the Yugo surplus is surfire and accurate. I still have some.
After reading responses to this post, I went and pulled the bullets from the 3 that FTF. The primers did not ignite. Also the powder used was trapezoidal flakes and the powder showed clear signs of deterioration averaging up to 10%.
The deterioration was more than likely greater in the rounds that hangfired.
Seems to explain everything to include the gross inaccuracy of this stuff.
I too was attracted to the low cost of this stuff and wanted to make sure fellow TFL guys knew what to expect.