Was out on Sunday with my .264 shooting the 130 Scirocco. All that is available from Swift and BulletFlight is the G1 BC of .571

I was coyote hunting and it was dead. I was driving a road that ended up being washed out in a ravine. I stopped there and looked down the ravine that had some really tall cut banks. I ranged a couple of objects that stood out at two locations and decided to test the drop data I had.

I had tested data with this combo out to 900 and it was pretty much right on. I lasered the first bank with a little black hole on it at 532, dialed it and shot it with a rest off of the hood of the truck. The muzzle brake eliminates recoil even with the .264 to the point that it feels like a .243 and you can watch bullet hits. It was a hit.

I then lasered a bank waaay out there; there was a white streak on the side of the bank that was obviously hawk chit. It made a good target at 1075 yards. Dialed the data I had and was quite low; about 2 feet. I dialed to the hit to adjust and had to add about 4 minutes to to my G1 data to have the right elevation for the next shot. I thought maybe the scope wasn't functioning properly.

Took it to Charley who threw it on the jig to test the scope. It was dead on perfect with upward travel till the dial stopped at about 35 minutes of perfect travel, not even veering to one side of the vertical line at the end. The Leupold scopes really are good.

We had a discussion about shooting really long ranges and we determined that the problem could be the use of the G1 BC. I called Swift and talked to the owner, who really is a great guy. We had a long conversation. He said they have never developed G7 BC's for any of their bullets.

I posted the question looking for the G7 on Snipershide and a guy replied with the G7 straight from Brian Litz's book "Applied Ballistics". I plugged it into BulletFlight and JBM and both spit out a much more accurate data card to actual drop.

The book would be a great investment to anyone shooting extreme long range.

RCA
I've always used G1 data because it was readily available. At 600yds it was always good enough. That said, I have to agree that at 1000 yds I'm always a bit low, usually around 2 minutes. Since I mostly shoot paper at known distance, The allowed sighters enable me to make the correction into the X ring. I then use that come up in the future for targets at the same range location. Based on your post, I'm going to run the ballistics on G7 and see how much difference it makes....Could result in less sighting shots and a little more time to wait on conditions in a match.

BTW, for anyone using the 6.5mm 130 Swift Scirocco, the G7 BC is .251 average

JBM's ballistics program has an option to change the G1 to other drag functions. It's the best way to go for long ogive boattailed and flat-based bullets IME.

Border Barrels website has a G1/G7 as well as a custom input section to generate your specific BC.

One note, a two foot drop at 1075 yards is not a big deal, a MV standard deviation of only a few Foot/seconds will induce more than that!

Also, what was the relative Humidty and station pressure from your data collection/zero to the conditions of the shot?