If the 'spare' striker assembly is to be a replacement for one of your Sav 99s, why not disassemble one of the bolts all the way down to bits to see exactly how the striker assembly is put together?
A few years ago, I replaced a drilled and pinned 'hammer' for a pre-mil EG by first examining the original assembly. I also obtained a NOS hammer from Numrich and it required that a pin hole be drilled. It was not difficult to do and using an accurate drill press, drill press vice, proper drill bit, and center punch prevented drilling the hole off center.
Aligning the hole in the hammer required careful measuring and marking. It helped to have the original hammer in hand.
The NOS hammer may also require adjustment of the FP protrusion from the bolt face.
