Balistics ? 180 berger 7RM

[upacreek]

I was messing with my col this weekend. When I zero my rifle at 200 and record the weather and important data then later shot longer distances I am always shooting high. Saturday I took a known load that had been accurate to 400yrds and shot out to 712yrds. This was at a range near my house. Range guy told me the gong was 725 yrds. My range finder showed 712, 714, and 712yrds. Look angle was 8* up. Entered everything into shooter and came up with 12.8 moa. Shot was spotted high. Moved down 1/2 moa. Still on the gong, but high and 2 o'clock 1/4moa left, and 1/2moa down and hit the 4" bulls eye. Followed by another to verify impact.
So my question is what do i do to calculate shots? Chrono claims 2960. Verify to 500yrds came up with roughly 2990fps. My shooter app was still set on the 2960 setting, but when adjusted up to 2990fps it still doesnt come up with the 1moa discrpancy.
I know I need to shoot some more ranges to verify this better, but dont want to waste ammo and time.
What is my next step??????
My thinking is to set up targets at 400 through 1000 every 100yrds and shoot 3 shot groups to get an average. Thats a lot of shooting. Anyone have better ideas?

 

[upacreek]

BTW I have up to 1500yrds behind my house to set up, but its a slow process setting up targets.

 

[c_bass16]

I personally prefer 100 yd zeros, but that's a topic for a different day.

Set up 200 and zero so you're 100% dead nuts on the money perfect.
Put plates or targets at 500, and 800 so you KNOW for sure that is the range. Not just what someone tells you.

Get on target, and then shoot a 3 shot group at both, recording where you impact on the target and what you had to dial in order to achieve it. (thats only 6 shots total)

Using either JBM, or your ballistic app of choice that has a velocity truing function. (I use Shooter.)
Plug in the numbers and get your true velocity. I'm betting your over 3000 by a fair bit.

Theoretical example...using my atmosphere...

Chrono says 3024 fps with 180 Hybrids, zeroed at 100 yds.
27.45 inHg
30 degrees
50% humidity

At 200 app says .4 Mil and I actually need .4 Mil
At 500 app says 2.3 Mil and I actually need 2.2 Mil
At 800 app says I need 4.7 mil and I actually need 4.6 Mil

By plugging the ACTUAL elevation to get on target, into Shooter, with my atmospheric data.
I conclude that I'm actually traveling closer to 3066fps.

SO, I would adjust my velocity and shoot out to, lets say, 1000.
With the new data...the app says 6.6 Mil.

If I impact significantly high or low. Then I would also inupt that data into my app, and re-verity.
Ideally, you would want to run that test out to your transonic range...but personally. I'm not accurate enough at that range to make the data valuable.
I usually only go out to 1200...but about 3 distances are enough.
One just past your zero, one medium and another either at transonic, or as far as you can accurately hold good groups.

I think your issues are coming from not going far enough out when you're confirming your velocity. It's not far enough to see significant change.

 

[thekyrifleman]

Have you checked your scope adjustments?? True??

 

[pyroducksx3]

The applied ballistics app, just the uprgradded shooter, has a function that allowes you to input 3 different distances and figures that curve out and gives you the figures you need. It's called ballistic calibration

 

[pyroducksx3]

I run the 180 berger in a 7 mag also and had to fiddle with the applied ballistics app quite a bit to get it to work. But running it with g1 ballistics on Bulletflight has proven to be right on.