Hi and welcome to STB
I had a small input into the SCB reticle used in the MTC range of scopes (the floating cross in the centre) and was given a 4-16x50 Viper by way of thanks (albeit in black)
I vaguely remember that the 4-16x50 Viper was available in Silver at that time although it doesn't seem to be an option now from what I can find on the web.
I'm not too sure what the rules are for hunter division ( is anyone?
) over on your side of the pond, but the issue of temperature sensitivity will be dependant on what method you intend to use for range estimation.
Temperature sensitivity seems to be a problem that is unique to range finding by parallax adjustment (a purpose that most scopes aren't designed for) so if you're not range finding by parallax adjustment then you won't have a problem with a black scope anyway.
For example, if you're bracketing (I believe you call it 'milling' over there) then temperature sensitivity won't be a problem at all.
If you could outline the rules regarding scopes for Hunter division - you've said it's max 12x mag, are you allowed to adjust parallax at all or is there a limit - i.e. you can only adjust parallax between lanes etc.
Are you allowed to adjust magnification during an event?
Are you allowed to adjust the elevation turret during an event?
Do you use bracketing and what do you bracket on? Kill zone size / faceplate etc?
Do you use any other methods of rangefinding inlolving the scope?
All the best