Dope help

[KY_coop]

Me and a friend went out and shot at a buddy's farm this weekend trying to stretch our rifles out before we try our first nrl hunter event. We were able to get a target out at 820 yds. This is the first time I've shot this load and rifle past 450 yds so I used some old data and adjusted from there. We found our dope and packed up. Tonight i enter everything in my ballistic apps and none of the data is making sense. All the calculators I've typed the data into have my drop data .4 mil higher then what was hitting. I'm hoping maybe one of you can point out an input or something that I've missed. Every other rifle,load, etc ive tried on these apps have been within a tenth at most distances.
Load data/ environmental is
6.5 140 match burner (.522g1-.288g7) @2780fps scope height is 1.85" 1/8 twist
790' elevation 35°f 70%hum and 29.92in hg.

6.0 mils is what was hitting at perfect height but strelok and wez both call for 6.4 mils. I tried adjusting velocity to see if maybe the garmin was off a little bit, no beans, looks like according to them velocity would need to be around 100 fps faster to get a 6.0 mil solution.
I haven't run into this before, is there an input I could obviously be missing, maybe adjusting the bc? I figured someone on here would probably be able to get me back on track if you got the time to run the numbers I would appreciate it.

 

[justinspicher]

I had a similar issue today as well. I did an approximate MV for my rifle and built a dope card.

Confirmed it and I’ve been using that data for about two years now.

Today I used a chrono for the first time and it’s significantly slower than I estimated, yet when I input this new MV, my dope is between 3-3.5 MOA lower than what I had. I was missing everything low so I ended up going back to my old data.

I checked and recheck all the data I put into my ballistic calculator and it makes no sense to me why this isn’t working.

 

[KY_coop]

I believe my garmin is atleast close on velocity. It reads within 5-10 fps of what my magnetospeed did on a different rifle and that magnetospeed read similarly to a different garmin unit. I've also thought maybe the bc needs to be adjusted, but I feel like the bc would be a little lower, if anything then advertised.

 

[hereinaz]

If it is user error, start a complete new gun and bullet, etc. Sometimes, I see people adjust something that they didn't understand at the time, or did it accidentally.

If that doesn't work, then sometimes the ballistic apps can't manage to give you a good solution. The ballistic apps work off of a made up "aerodynamic model" of a bullet and maths. Sometimes, the model/maths don't work perfectly. The "G1" is a model based on a flat base bullet and the "G7" is based on a pointy boattail bullet. But, out to transonic it doesn't matter which you use.

Check your BC, make sure that it is correct. You don't want to input the G7 BC which is a lower number than the G7. Did you use the CDM in WEZ?

If nothing else works, adjust velocity so that it matches your actual DOPE. You have to watch out that you adjust it so that it is good for all of your DOPE at various distances.

You can also put your real world data into the app Gravity Ballistics. It builds a dope chart based on YOUR dope, not the made up model based on G1/G7.

 

[hereinaz]

I had a similar issue today as well. I did an approximate MV for my rifle and built a dope card.

Confirmed it and I’ve been using that data for about two years now.

Today I used a chrono for the first time and it’s significantly slower than I estimated, yet when I input this new MV, my dope is between 3-3.5 MOA lower than what I had. I was missing everything low so I ended up going back to my old data.

I checked and recheck all the data I put into my ballistic calculator and it makes no sense to me why this isn’t working.

Believe the bullet, it has to fly in reality. The ballistic calculators work in a made up world based on modeling. Sometimes, it just needs some tweaking. And, consensus is adjust your velocity to FORCE the model to fit reality.

Its one reason why Gravity Ballistics makes sense, the app made by Frank Galli at Sniper's Hide for exactly this reason.

 

[KY_coop]

I'm not super familiar with wez yet, I've only messed with it a couple times before tonight. Strelok, hornady app, and kestrel is what I've used in past. As far as the g1/g7 i selected the bullet on the apps and it was automatically input. I will try the gravity ballistics as well as rebuilding the profile to see if I come up with something different.

 

[hereinaz]

I'm not super familiar with wez yet, I've only messed with it a couple times before tonight. Strelok, hornady app, and kestrel is what I've used in past. As far as the g1/g7 i selected the bullet on the apps and it was automatically input. I will try the gravity ballistics as well as rebuilding the profile to see if I come up with something different.

It could just be you need to adjust velocity. Don’t bang your head. It happens.

 

[KY_coop]

Would adjusting the velocity up almost 100fps seem like to much or is that normal?

 

[Castle Rock]

The issues are generally due to input parameters
Sometimes you have to delete the app and start again

 

[davsco]

did you go to bullet mfg's website and confirm the bc's?

meters vs yards?

100yd zero?

double confirmed your target distance?

 

[Wrench]

What terrain were you shooting over? Has the rifle been tall target tested?

I've seen the above occur due to terrain features with up currents, although .4m in 800 is on the top end of that.

I trust the chronographs to about 1%, garmin says .1%.....so if I see a shift beyond 1%, I start looking beyond the velocity.

820yds is well inside the supersonic range, so bc variation is not likely to be more than a few hundredths, which will fall in the margin of error for most shooters

The last component comes down to the optic. There's a chance parallax can cause a good bit of shift.....perhaps .2m (ish). Did you try shooting at lower and high power? If so, did you see a shift?

The last component is rifle fundamentals. 800 is a poke and will certainly let you know when you are doing it wrong. Did you shoot any groups at the 820? Where did they land and how big was it?

 

[HandgunHTR]

Published BC and actual BC don't always match up (just ask long range hammer users).

I would adjust your velocity up in the app, and then verify at multiple distances. If it is on, then roll with it.

 

[dieselchessy]

Ran your numbers on Shooter, it agrees at 6.4 mil.

Do you have a good zero? Moving the 100 yard zero up 1” looks to correct the data.

Does your scope dial accurately? What brand/model scope?

Did you only shoot 820 that day or did you confirm other distances as well?