Ballistic truing anomaly

[307_timberstalker]

So when out trying my calculator I started with my confirmed zero at 100 yards. I moved over to 500. Inputted all my data and got my moa drop. I dialed and shot. About 9” below the water line. Second shot. Same poi. 3rd shot. Same elevation but just left of the other two shots. OK. I dialed up till I was on the line. Made note of my change. Changed MV till my drop was what my dial was showing. Next I shot at 700. No impact. Played back the footage and I was a foot over the target (at least) weird. Took a second shot. Same. Miss high. I then put back in my original known MV from my magneto avg and dialed for 700. Centerline left edge of target but perfect elevation. Ok I thought I’ll leave my MV and try at 800. Go to 800. First shot. Miss high. Second shot, miss high. Dial down till I impact on the water line. Mark my adjustments and this time I decided to start changing my BC. From a berger 220 with a G1 of .717 I had to change to a .900 in order for my dope to match. Thinking this was really extreme I ran shots back down from 800, 700, 600 and even 500. Each range i was on or just slightly above water line.

Everything I read or have been told is that you must adjust MV inside of 1,000. Some say 800 but either way. What I noticed is that at 500 I was low. Way low, but the further out I’d go the bullet wasn’t dropping as calculated. When I adjust my MV for 500 to hit waterline I was moonballing rounds over the 7 and 800.
What am I missing? I feel like I have it where she needs to be but this small part of me is saying I’m missing something here? Thoughts?

300 prc 24” C6
220 berger hybrid
2850 fps avg.
8.4 SD 12 ES

 

[wakedye]

What scope is on the rifle? Do you know if it tracks correctly?

 

[zrodwyo]

I wouldn’t mess with the magneto speed velocity - it’s going to be close enough. Why screw with one of the only known variables?Your BC is not .900 so there is something wrong with your inputs. Here is what what I would do:

1. Make sure your zero is as perfect as you can get it.

2. Check all your solver inputs

3. If those are good and assuming you don’t have some kind of mechanical issue (doesn’t sound like it) work on your form. I have rifles I can miss high or low depending how much I lean into the gun. Heck you can miss an MOA high at 800 from mirage alone this time of year.

My guess is you have something messed up in your ballistic solver.

 

[Reburn]

I agree with above.

In my order of problem solving.
1) check the profile for errors. I have even gone as far to delete and just reinput so I dont get snow blind looking at numbers.
2) check zero. 20 rounds take MV with my labradar same time.
3) True MV to match inside 1000 yards if correction is less than 30 fps or so from the lab radar
3) never touch BC. I dont shoot far enough to worry about that. 1200-2000 yards.

I will walk the gun out 3-5 shots every 100 yards from 400-1000. I track and write down the groups. If I see a trend low or high at every distance I might make a correction on the scope rather then the program.

I have never done all of this and not had a gun true up.

 

[ResearchinStuff]

sounds like a scope tracking problem. magneto's should be in the right ballpark for speed, and that's not a .900 G1 BC bullet.

 

[307_timberstalker]

I believe I may have found the issue. In my app (ballistic AE) in atmospheric conditions I had the pressure is absolute. This is for my .900BC profile mind you.
When I cross referenced to the same profile minus absolute pressure and back to .717 BC they’re almost identical. If I change the pressure back to absolute pressure it changes drastically where my 500 and on are a full moa or more off.

 

[hereinaz]

Tall target test for scope error. Double check the actual range, too. Create a brand new profile for your rifle.

Low at 500, then after you adjusted MV to hit 500, you were then high at 700. That is what I would expect if there was a scope tracking error and tried to fix it with MV.

Post screen shots of your data, and we can play with the math.
You maybe can test your data for scope tracking and see if that makes more sense than velocity. Some of the apps have an input for scope tracking error.

 

[hereinaz]

I believe I may have found the issue. In my app (ballistic AE) in atmospheric conditions I had the pressure is absolute. This is for my .900BC profile mind you.
When I cross referenced to the same profile minus absolute pressure and back to .717 BC they’re almost identical. If I change the pressure back to absolute pressure it changes drastically where my 500 and on are a full moa or more off.

User error, been there.

 

[307_timberstalker]

As Seen here, it’s the same profile same numbers but 1 is pressure absolute the other is not. Basically I had pressure is absolute and when I knew my MV was known I just kept changing my BC input till my hits were true. Which now when I re-do my profile, the absolute pressure turned off, BC of .717 and true MV…it matches what I created last week WITH absolute pressure and .900 BC which yes we all know it isn’t a .900 BC

 

[ResearchinStuff]

glad you sorted it out.

 

[307_timberstalker]

glad you sorted it out.

Well for the most part yes, still wondering if I don’t have a tracking issue though. That’ll be my next test.