Casey its not necessarily a standardised droop, as said time and time again it depends upon the actual scope used.
By that all scopes have a massively different optical centre none worse than the BSA/Niko from one to the next. Some Niko been known to have optical zero at 71MOA whilst others 26MOA who knows.
Its the same across the manufacturers, theres no set standard though Falcon and S&B tie in repeatedly with same amount which is a lot more than 16MOA, in turn closer to March optical zero but way too much for most Leup models.
I know the exact optical zero for most well made scopes.
Check those QRW fit picatinny MOD Spec 1913. Burris are good so are Third Eye and Kelblys.
Cant beat a properly cut dovetail offering more grab.