Need advice from tech savvy people on numbers I’m getting

[david g ranes]

A friend and I were shooting Friday at 400 to 690 yards we were both shooting 22 creedmoor 85.5 grain Bergers we both have magneto speeds we were shooting to verify our yardages according to my magneto my velocity was 3232 on dougs it was showing 3252 but according on my geo ballistics app my true velocity was 3321 my Mia at 690 was 10.1 at 400 it was 7.3 if I remember right with out going to look now here is the kicker dougs was showing for a trued velocity was 3187 but his number of clicks to hit at 690 was 2 less than mine and the magneto speed showed his velocity was 3314 my dope I put in this app for my other guns are spot on with the magneto velocity so I hope some body is smart enough to give me some kind of answer I can understand. Thank. David

 

[idcwby]

It sounds like you have a zeroed weather function already in there and it was adjusting speed based on your current weather conditions, while you were shooting. I've never played with Geo, but this is what it sounds like from my experiences with Strelok and a few others.

 

[lancetkenyon]

Could be your BCs are off too. Twist rates effect BC.
Zero might not be exactly as programmed.
Scope height above bore might be slightly off.
Look angle effects actual drops/distance.
Winds effect drops.
Mirage effects actual POA.
Recoil management effects POI.
Preloading bi-pod? Cheek weld?
Weather conditions. Temps, altitude/DA, even sun angle.
Parallax adjustment.
SFP or FFP scope?
Turret clicks could be off. Have you run a tall target test to verify?

 

[Shane Lindsey]

It's all voodoo!!!

Agree with above. My vote is BC is slightly off for your barrel.

 

[david g ranes]

It's a brux barrel on mine and an x caliber on his it just seems like it is giving so much difference I didn't understand I contacted the company at geo they didn't have an answer the only difference my barrel is a 4 groove and a thousands tighter bore my scope was tracking at two hundred I move it ten inches that's where it went this is the only gun that the chrono isn't matching my drop validation and I think in puts would have to be off considerable to be off 100 ft a second don't really matter because my data I collected is right I just don't like to not understand what is different. Thanks David

 

[david g ranes]

It's all voodoo!!!

Agree with above. My vote is BC is slightly off for your barrel.

How much bc to make a hundred ft a second difference Bergers bcs have always worked for me out to a thousand. David

 

[Shane Lindsey]

Were you shooting at 490/600 with the Magneeto on it?

According to my free iphone app, this is what I came up with.

Based on what you give in your post. (My input data is for sea level)
85.5gr Berger
G7 BC .268 Assuming you have a 7.25 twist.
Muzzle Velocity 3232 FPS

3232 FPS Muzzle Velocity=400 yards 2553 FPS, 4.4 MOA... You state you needed 7.3. - 11.6 inches difference??? (You may want to look at your notes as I think you may have different numbers as this seems a bit off)???

3321 FPS Muzzle velocity=400 yards 2633 FPS, 4.1 MOA.

3232 FPS Muzzle Velocity=700 yards 2099 11.6 MOA... You needed 10.1. -10.5 inches difference. I could understand this as this POA is very small at that range.

3321 FPS Muzzle velocity=700 yards, 2171 FPS, 10.9 MOA.

Not sure why you needed so much correction at 400 and it didn't translate out to 690. Either way my comeups are still less than what you needed.

How was the mirage? That can affect your aim point especially if coming off the barrel and down range.

No offense, I think your aimpoint may be the issue. I watched a video where I guy was truing and drew a line across the target to give him a refined aim point. I have done similar with an large orange dot and aimed where the white and orange met instead of in the center of the orange for refinement.

 

[david g ranes]

Were you shooting at 490/600 with the Magneeto on it?

No sir. David

 

[P7M13]

Magnetospeed Is a direct measurement.
The others are calculated.
Who you gonna trust?

 

[david g ranes]

Our come ups are on but they sure don't match what the chrono is telling us and everything else we have the chrono is very close just trying to figure out the big variance on these 2 guns. David

 

[david g ranes]

Were you shooting at 490/600 with the Magneeto on it?

According to my free iphone app, this is what I came up with.

Based on what you give in your post. (My input data is for sea level)
85.5gr Berger
G7 BC .268 Assuming you have a 7.25 twist.
Muzzle Velocity 3232 FPS

3232 FPS Muzzle Velocity=400 yards 2553 FPS, 4.4 MOA... You state you needed 7.3. - 11.6 inches difference??? (You may want to look at your notes as I think you may have different numbers as this seems a bit off)???

3321 FPS Muzzle velocity=400 yards 2633 FPS, 4.1 MOA.

3232 FPS Muzzle Velocity=700 yards 2099 11.6 MOA... You needed 10.1. -10.5 inches difference. I could understand this as this POA is very small at that range.

3321 FPS Muzzle velocity=700 yards, 2171 FPS, 10.9 MOA.

Not sure why you needed so much correction at 400 and it didn't translate out to 690. Either way my comeups are still less than what you needed.

How was the mirage? That can affect your aim point especially if coming off the barrel and down range.

No offense, I think your aimpoint may be the issue. I watched a video where I guy was truing and drew a line across the target to give him a refined aim point. I have done similar with an large orange dot and aimed where the white and orange met instead of in the center of the orange for refinement.

Ok my come ups were 13 clicks at 400 7.1 Moa at 580 10.1 moa at 690 all of these are hitting perfect but if you use this information on the trajectory validation it shows my velocity as 3321 not 3232 like the magneto says dougs is opposite he's showing 2 clicks less than me but a slower velocity on the validation on the magneto he's showing 3312 on his validation at 690 shows 3187 his velocity shouldn't be coming up slower than mine if it takes 2 clicks less for him to hit dead on at 690 don't know how to explain any better had to be something simple trying to figure out what on other ballistic calculators saying same for my gun don't know about his but every other gun I have the magneto has worked well for my velocities we have two of them that are reading very close to each other. David

 

[Shane Lindsey]

That's why it's voodoo!

All the calculators I have used, NONE have been dead on once I stretched out past 600. All had to be tweaked a bit.

 

[david g ranes]

Were you shooting at 490/600 with the Magneeto on it?

According to my free iphone app, this is what I came up with.

Based on what you give in your post. (My input data is for sea level)
85.5gr Berger
G7 BC .268 Assuming you have a 7.25 twist.
Muzzle Velocity 3232 FPS

3232 FPS Muzzle Velocity=400 yards 2553 FPS, 4.4 MOA... You state you needed 7.3. - 11.6 inches difference??? (You may want to look at your notes as I think you may have different numbers as this seems a bit off)???

3321 FPS Muzzle velocity=400 yards 2633 FPS, 4.1 MOA.

3232 FPS Muzzle Velocity=700 yards 2099 11.6 MOA... You needed 10.1. -10.5 inches difference. I could understand this as this POA is very small at that range.

3321 FPS Muzzle velocity=700 yards, 2171 FPS, 10.9 MOA.

Not sure why you needed so much correction at 400 and it didn't translate out to 690. Either way my comeups are still less than what you needed.

How was the mirage? That can affect your aim point especially if coming off the barrel and down range.

No offense, I think your aimpoint may be the issue. I watched a video where I guy was truing and drew a line across the target to give him a refined aim point. I have done similar with an large orange dot and aimed where the white and orange met instead of in the center of the orange for refinement.

No mirage and I built plexiglass crosses years ago that go from 2 inch cross to 9 inch cross 2 inches wide for longer distance hold it on the steel and paint I always put my cross hair on the edge to match the cross impacts didn't very an inch up and down did have a slight cross wind about one moa worth. David

 

[Timnterra]

It's most likely your scope. These questions pop up all the time "my drops don't match up with what the ballistic calculator says"
I'm going to wager a guess that your scope tracks repeatable but not true to actual numbers. So when you are turning 1 moa on the scope it is actually moving the reticle 1.1 moa or something like that. That is actually a big deal being a 10% error and oddly many scope manufacturers are ok with that. I'd do a tall paper test to see how the scope tracks and adjust the values in your ballistic calculator to see if it agrees with the magnetospeed.