When the range is doubled, shot group sizes will at least double. For each 100 yards of range past 100 yards, groups get about 10% to 15% bigger due to velocity spread, subtle invisible air movements and bullet BC spread.
5" to 6" drop at 200 yards when zeroed at 100 is about normal for .308's. Without knowing what a "light" load is, it's hard to estimate.
What you've done at 100 yards is pretty good.
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Former US Navy & Palma Rifle Team Member
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