Berger calculator issue

[Muley crazy]

To qualify the title the Berger calculator is probably correct,,,, Here is the issue. 277 diameter bullet with G1 of .339. Berger 170 Gn elite long range- Magneto speed readings of 2800-2820. Zero on the rifle at 100. Shot this weekend at 500 yd F class match, The calculator says 8.58 MOA , and the reality of the problem, the NF scope setting is 10.75 moa to be on the X, The sight height is 2.25. To get to the proper moa that the rifle is shooting at 500 yards I have to back the speed off to 2555 fps , the powder charge is 58.40 of H1000. 14k off the lands, What am I missing? Magneto wrong? The charge speed is what I expected and the gun is shooting 1/2 moa

 

[_Windrider_]

What’s the MV on the box where that .339 BC came from?

 

[BigTex]

To qualify the title the Berger calculator is probably correct,,,, Here is the issue. 277 diameter bullet with G1 of .339. Berger 170 Gn elite long range- Magneto speed readings of 2800-2820. Zero on the rifle at 100. Shot this weekend at 500 yd F class match, The calculator says 8.58 MOA , and the reality of the problem, the NF scope setting is 10.75 moa to be on the X, The sight height is 2.25. To get to the proper moa that the rifle is shooting at 500 yards I have to back the speed off to 2555 fps , the powder charge is 58.40 of H1000. 14k off the lands, What am I missing? Magneto wrong? The charge speed is what I expected and the gun is shooting 1/2 moa

You are using the wrong BC. For that bullet at that velocity the G1 is .676 and the G7 is .335.

http://www.bergerbullets.com/introducing-the-berger-270-caliber-170-grain-eol-elite-hunter/

 

[_Windrider_]

You are using the wrong BC. For that bullet at that velocity the G1 is .676 and the G7 is .335.

http://www.bergerbullets.com/introducing-the-berger-270-caliber-170-grain-eol-elite-hunter/

Yep. .339 looks more like the G7 BC

 

[Muley crazy]

The G1 and the G7 each give the same results at 500 yards. 8.65 and change, that's the confusing part. I confirmed the magneto speed 2816 last evening, However to get to the bulls eye at 500 it takes 10.75 MOA, I appreciate any help to resolve this.

 

[_Windrider_]

The G1 and the G7 each give the same results at 500 yards. 8.65 and change, that's the confusing part. I confirmed the magneto speed 2816 last evening, However to get to the bulls eye at 500 it takes 10.75 MOA, I appreciate any help to resolve this.

Does changing the BC to what @Travclem suggested get you closer? It might help if we see how you set your rifle up in the app. often the mistake is in the setup (wrong sight height, twist rate, etc.)

 

[Muley crazy]

The Berger calculator doesn't have a entry for the twist rate, It's a 25 inch Brux 1-8. Chamberd in 270 Winchester , All the calculator speed has to be dropped into the 2575 2555 range to get the calculators to match, the sight height is measured from center of bolt to center of scope tube, once again rifle shoots lights out, until the number 3 contour gets hot then she gets a little sloppy, I am adding another 1/2 minute into it after a ten shot string at the 500 yd line, that puts it at 11.25 moa , I know I'm missing something, I have a 300-500-600 F class match this weekend and the rifle is a wonderful thing cold bore, X's and 10's. Just need the right dope so that I'm not heating the barrel up chasing the set up, Two weeks I have a 5 rounds at 1000, that will be easier.

 

[_Windrider_]

Give me this info and I’ll see what AB says

 

[Muley crazy]

Brux 1-8 cut to 25 inch, right twist, 270 winchester, sight height 2.25. Night Force 8-32 power rear focal plane MOAR, Average magneto speed 2816, zero is at 100 yards , Berger 170 Gn extream outer limits hunter, G1 is .662. G7 is .339. Sighted and matches at 85 farenheight at 600 ft elevation high humidity, 70 percent, Norma brass annealed every reload GM 210 primers, Necks turned to 12K, bullet seated 15k from the lands, All the calculators I try say 8.65 and change, at 500 yd, NF has to be at 10.75 cold bore, 11.25 after it gets hot, I expected 2800-2850 out of the 58.40 Gn of H1000, fills case to what looks like 95-98 percent, bullet seating is not compressing the charge,

 

[_Windrider_]

im away at the moment. i will plug it in when i return home and see what it says. in the meantime, maybe try JBM ballistics online for free.

 

[Muley crazy]

If you don't mind I would like to call you after you run the numbers, can I call? My e mail is [email protected] if you could send contact info there

 

[_Windrider_]

Yeah no problem. ill PM you my number when i get home.

 

[Muley crazy]

So problem had been solved, I was sighting the rifles in with a magneto speed strapped to the barrel , on the 270 win this was creating a 2.5 moa miscalculation in the lower direction, so a 2.5 moa come up at 100 yards to re zero, It's still shooting bug holes after re zero 1/4 moa at 200 yards, Thanks for the replys and thanks to Berger and Nightforce for the help sorting this out, and of coarse tacticledillhole for taking the time for your thoughts.