ballistics program question

[Headquarterz]

The delimma-
I ran shooter on android and jbm on the computer for a 284. The muzzle velocity was 2885 through a CED m2. I input all the required parameters like sight height above the bore. The load was a Berger 180vld. 4831SC powder. Seated touching. My es was under 10 fps for a five shot group.
Anyway, I allow shooter to populate environmental conditions. Calculate and pull up the drop chart. The problem is, my calculated drop is slightly more than the actual hard data I'm accumulating by shooting.
For instance, everything is within 1/2 moa out to 500 yards. Then the drop calculated by the programs starts increasing more at each distance. At 610 it does up 10.3 moa but I dialed only 8.25. At 760 called 14.8 and dialed 13. 900 19.6 dialed 17.5. 1020 called for 25.25 and I dialed 22.0.
I don't know what I'm missing. I haven't run a box test at 100 with this scope but similar differences were found with a 7stw and a243 with different scopes. The differences are consistent on all 3 guns.
Any ideas. I'm thinking it might be something simple. But who knows. Thanks

 

[CleanMoostang]

Computers only do so much. I didnt really like shooter but Ballistic AE has a feature that lets you put in ur actual drop vs what its telling you and it corrects your drop chart for you.

Are you using the right Bc and drag model?

 

[db_17_85]

Shooter also lets you correct your dope. In the table, it's labeled as MV Tool. (on android anyhow)

 

[Headquarterz]

Yes. I'm using the correct drag model and BC. I tried g1 and g7 with litz and Berger's numbers. Same thing.
I don't expect it to be perfectly dead on . I just don't understand why 3 different Cartridges are being calculated incorrectly in the same fashion. Appreciate the replies.

The muzzle velocity tool isn't on shooter any more. I couldn't find it. Besides, if I increase my MV, it throws my calculations off Under 600 yards.

 

[Joop]

I'm not familiar with Shooter, but the first thing I would check would be altitude and temperature. In particular, the temp when zeroed vs. temp for your current shooting and see if there is a difference there.

 

[waveslayer]

Yes. I'm using the correct drag model and BC. I tried g1 and g7 with litz and Berger's numbers. Same thing.

Shooter has the MV. He updated it. Trust me. I just used it and it worked out great.

 

[Headquarterz]

Found the MV tool. It's not on the graph on mind. Back to the load data and hit menu to get to it. I tried it and things are looking more in line with my dope. Thanks. Maybe the chronograph is off.

 

[Ring]

Yes. I'm using the correct drag model and BC. I tried g1 and g7 with litz and Berger's numbers. Same thing.
I don't expect it to be perfectly dead on . I just don't understand why 3 different Cartridges are being calculated incorrectly in the same fashion. Appreciate the replies.

The muzzle velocity tool isn't on shooter any more. I couldn't find it. Besides, if I increase my MV, it throws my calculations off Under 600 yards.

yes it is...

 

[Ring]

Yes. I'm using the correct drag model and BC. I tried g1 and g7 with litz and Berger's numbers. Same thing.
I don't expect it to be perfectly dead on . I just don't understand why 3 different Cartridges are being calculated incorrectly in the same fashion. Appreciate the replies.

The muzzle velocity tool isn't on shooter any more. I couldn't find it. Besides, if I increase my MV, it throws my calculations off Under 600 yards.

FYI, if your dope for under 600 is dead on, and out to 1k is off, if u adjust it for 1k, and under 600 is off, in can 99% guarantee you your scope tracking is fubar...

what scope?

 

[Headquarterz]

yes it is...

Yeah i found it. The muzzle velocity to used to be accessed from the graph by hitting menu, then velocity tool. Now it's in the environment menu bar. Thanks

 

[Headquarterz]

FYI, if your dope for under 600 is dead on, and out to 1k is off, if u adjust it for 1k, and under 600 is off, in can 99% guarantee you your scope tracking is fubar...

what scope?

Sightron s3. But the other rifles had a vortex PST and a zeiss . the one thing linking these rifles together was the chronograph , CED m2 with infrared sky screens, and all three of our shooter apps were off at the longer distances. Like the old adage says, junk in, junk out.

 

[Ring]

Sightron s3. But the other rifles had a vortex PST and a zeiss . the one thing linking these rifles together was the chronograph , CED m2 with infrared sky screens, and all three of our shooter apps were off at the longer distances. Like the old adage says, junk in, junk out.

so, are u saying 3 different rifles with the same issue?.. or same gun, 3 scopes?

can u post your data,
bullet
fps
alt.
temp
scope hight
actual dope at 300,600,800,1000

also, read this...

Ballistic Program Inaccuracies

 

[Headquarterz]

My 284 Shehane has a sightron s3. The environment is
2650ft
61 degrees
71% humidity
Barometric pressure 29.91

The rifle
Eliseo tube
180 berger vld hunting
MV 2885
Es <10
Consistently groups .2's and .3's at 100
Scope height 3.11"
Dope
100 yard zero
200 1.5 moa
300 2.5
410 5
520 7.25
610 8.5
760 13.25
900 17.5
1025 22.25
After running the velocity tool in shooter it calculated the MV to be close to 3000 fps. I don't think I'm pushing it that hard. Not with the powder and charge weight I have settled on.

 

[Headquarterz]

The 243 has a Zeiss. I I'll have to get that data later today and post it. The program was 2 to 2.5 moa with that one as well.
These were all shot through the same chronograph under the same conditions. In thinking the chronograph may be wrong. With that said, my 284 velocity seems a little too fast after calibrating my actual elevation adjustments with shooter.

 

[Ring]

"calculated the MV to be close to 3000 fps."

ya, thats about a average if i put in the dope for each yardage, if i do it for each drop, i get

300 2.5 =2916
410 5
520 7.25 = 2916
610 8.5
760 13.25 = 3062
900 17.5
1025 22.25 = 3058fps

i would seriously do a tracking check on the scope

 

[Joop]

Again, what temp did you zero them at? What temp did you chronograph them at and did you chrony all three rifles/loads on the same day? If they're different from this last range session, is this difference represented/compensated for by Shooter (ie: zero weather vs. current weather)? If three different guns with three different scopes are all doing the same thing, I highly doubt it's a scope tracking issue (at least not for all three).