These are custom made Yugo/Zastava-style grip screws with the big flat head and a lock washer. These are the standard 6mm thread diameter, 1.0mm pitch and approximately 100mm long — about 96mm shaft and a 3.5-4mm thick head. These were used in the military M70, M72, M76, M77, M85 and M92 series weapons.
These are not the short stubby screws the modern Zastava rifles use in their commercial furniture. These are the longer Yugo military style.
The screws are black oxide coated stainless alloy that has a hardness of approximately 10.9. An external tooth silver lockwasher is included.
The gallery has a number of photos that show grips, nuts and additional screws purely for illustration. The grips shown are original Yugo/Zastava grips so you can see the size comparison.
Note: The one gallery photo has the new black grip screws by an silverish worn looking screw – that worn screw is an original Yugo screw from a M70B1 kit so you can see them side-by-side.