Just to illustrate my point from above, I keep a list of the popular bullets from major manufactures handy to make sure inputs are correct in calculators. This is my list sorted for highest g1 bc first. Now this is only the major manufactures and it is published data so take it for what it's worth, but it still shows that the highest 6.5 bullet available is about 17th on this list, lots of 7mm bullets above it and you can see the trend that the larger the diameter the higher the BC's get. .338 are higher on average than .30. .30 are higher than 7mm, 7mm are higher than 6.5.
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Nice spreadsheet. Thanks for sharing.