Don't get hung up on calibre. First time shooter I would suggest stepping down a little from the 308 unless its in a heavier rifle, (not that it's a bad choice) and look at 243 or 7M08.
Stick to common main stream established calibres to start with so you can get ammo anywhere. North island, 243,7M08, 308, Maybe the 6.5 CM , for south island some may want to step it up a little 270, 3006, 7mm Rem Mag etc etc etc.
Glass, 2-8, 3x9, 2-10, 3-12 etc, for bush shooting a bottom end of 1x to 3x power is good, 4x is starting to get to restrictive for bush work. Remember you may be needing to find your target in the scope at 10 mtr or less.
You will get better glass and quality internals with a scope that has a 3 or 4x zoom rather than a 5x zoom.
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