Question - Fire Control and Range Finders

[harlikwin]

I'm also curious as to the RF and FC question more specifically as it pertains to tank armaments.

Could someone post a general guide to what the currently accepted values are for both RF and FC numbers?

Please correct me if I'm wrong on any of this
I assume

For RF
For stadiametric type sights I'm seeing values typically under 10
For Ranging MGs the number is not 15 or 16?
For Optical coincidence type RF's the values are around 18? Except for apparently russian ones that are rated much lower ~12 on the T-64 (why? its the same unit used on the T72 listed as 18)
LRF 22

As for FC values Is there any criteria or ranges for these numbers? Or are we subjectively saying one system "seems" better than another? Or is it a more per decade thing? I can't quite figure anything out.


Also on an odd note Why is the T-54 (006, 007) FC 2 when the T-34 (004) has it as FC 3 (was the T-54 FC worse than the T-34 orT-44?)