Re: 2.5-10 or 1-4 for an spr
I'd prefer 2.5-10x for out to 600 meters,
but you said you'd like to do local carbine comps,
so I'd go with 1-4x for shorter range carbine comps.
You can still shoot 600 meters with 4x.
That said, I'd prefer a 10x with a mini red dot in an offset mount for the close fast shots.