Applied Ballistics vs Actual Data - Truing The Right Way

[Monk Medic]

Hello all,
The last two weekends I’ve shot the AI .338 Lapua gun at distance, and the last two weekends the AB data has been incorrect. This is a new rifle, so I’ve collected and documented data.

I’ve read numerous threads on here about “truing” data, but I’m still unclear which is the right way to correct.

Muzzle Velocity- I know that I can do muzzle velocity changes, but I’ve shot and used the Magnetospeec chronograph to get inital Muzzle Velocity when I first got the gun, so unless the MV has radically changed or my Magnetospeed is incorrect, I should be right on. Recorded as 2,681 FPS.

Ammo - I’ve shot the same Lapua 300gr ammo since the start.

Suggestions? My data and the AB projections follow:

My data - AB calculated
1,000 yards - U 7.3 mils AB - 7.9 mils
750 yards - U 4.5 mils AB - 5.0 mils
550 yards - U 2.7 mils AB - 3.0 mils
300 yards - U 0.8 mils AB - 0.9 mils
200 yards - U 0.3 mils. AB - 0.3 mils

 

[_Windrider_]

id start with truing the BC before doing large chnages to MV. the BC in AB is an average and the BC on the box is valid only at the given velocity they tested. if you are shooting faster, your BC is better and vice versa. tweak the BC in AB to match what you are actually shooting.

 

[Monk Medic]

I wonder how far I am off?
I did download the custom data, paid for, from AB.

 

[Deleted member 113831]

I would give the opposite advice from above. The reason is this...out to 500 yards, velocity is king in determining trajectory. As long as your assumed BC is in the immediate neighborhood of actual BC you are good to 500. Adjust velocity at 500 to match trajectory. Try to do this either very early in the morning or on a heavy overcast day or you will be introducing light variables into the equation that are difficult to account for.

Once that is done THEN shoot at the farther distances. Past 700 is where BC really starts to have a large enough effect to see a real difference.

If you were using something other than AB that gives you the option of inputting multiple BC's, you could create your own custom drag curve. I use Strelok Pro for that very reason. You can get the custom drag curves from AB. All that is, is them doing the BC banding for you, and it is still only thier best guess.

 

[lte82]

Set your velocity to 2780 fps and see how that looks.

Fwiw I just recently tried a few custom curves and the data worked really well out to 1000 elevation wise. +/- .1 mil at pretty much every distance.

Also to get 7.3 elevation at 1000 with 2680 fps / 1200 DA you would need like a .480 g7. I would tend to believe your velocity is off before I believe your bc is that high. At 2770-2780 fps my trued g7 is .390 for the 300 scenar in my 338 norma.

 

[_Windrider_]

I would give the opposite advice from above. The reason is this...out to 500 yards, velocity is king in determining trajectory. As long as your assumed BC is in the immediate neighborhood of actual BC you are good to 500. Adjust velocity at 500 to match trajectory. Try to do this either very early in the morning or on a heavy overcast day or you will be introducing light variables into the equation that are difficult to account for.

Once that is done THEN shoot at the farther distances. Past 700 is where BC really starts to have a large enough effect to see a real difference.

If you were using something other than AB that gives you the option of inputting multiple BC's, you could create your own custom drag curve. I use Strelok Pro for that very reason. You can get the custom drag curves from AB. All that is, is them doing the BC banding for you, and it is still only thier best guess.

Why would you change the velocity? He said he got it from the MS? Why change what is known to be good?

 

[Diver160651]

id start with truing the BC before doing large chnages to MV. the BC in AB is an average and the BC on the box is valid only at the given velocity they tested. if you are shooting faster, your BC is better and vice versa. tweak the BC in AB to match what you are actually shooting.

^ no that’s wrong. You’ll be completely jacked if you true BC to meet your data at the short ranges.

Turn up your speed as pointed out until your 300 550 line up ..

 

[Diver160651]

Why would you change the velocity? He said he got it from the MS? Why change what is known to be good?

No way he has a good velocity if his 300 yard and 550 yard drops are that wrong

 

[Deleted member 113831]

Why would you change the velocity? He said he got it from the MS? Why change what is known to be good?

Magnetospeed is much better than we have had in the past, but the error can still be 1% or so. That would be 27 fps with these speeds. Even if the unit itself is perfect, there is no guarantee that the operator didn't introduce an error in using it. The angle of the bayonet to the bullet path matters, and that changes with barrel taper and the way it is mounted.

 

[lte82]

Magnetospeed is much better than we have had in the past, but the error can still be 1% or so. That would be 27 fps with these speeds. Even if the unit itself is perfect, there is no guarentee that the operator didn't introduce an error in using it. The angle of the bayonet to the bullet path matters, and that changes with barrel taper.

Not to mention, the barrel could have sped up, the ammo lot could be hotter, the temp could be different causing a velocity change... 90 fps is a lot but ive seen a 70 fps increase just from barrel speed up from new to 400 rounds.

 

[christopher.dow]

I finally ran the AB numbers against what @TacticalDillhole and I collected in Ft Morgan:

Warner Flatline .308 160gn
BC: .589 (G1)/.294 (G7) from Hornady Doppler
MV: 2852
DA: 6000
SP: 25.3
T: 67.6
H: 23

Distance Measured AB JBM Trasol Hornady
200 0.3 0.3 0.4 0.4 0.4
300 0.6 1.0 1.1 1.0 1.1 <- Huh?
400 1.1 1.7 1.8 1.7 1.8
500 1.7 2.5 2.6 2.5 2.6
600 2.8 3.4 3.5 3.4 3.5
710 3.9 4.4 4.4 4.3 4.5 <- actually 711
800 5.0 5.4 5.4 5.3 5.6
900 6.0 6.6 6.5 6.4 6.8
1000 8.5 7.8 7.7 7.6 8.2

Clearly, Hornady is closest. I haven’t been able to get the BC to true any of these. It’s possible we had the distances wrong, but we’d been shooting on that range for two days already, and I think @TacticalDillhole was using my range finder. He was also using my spotting scope with mil reticle, so he was giving me good corrections.

So did the time-traveling Chinese put a gravitational anomaly on @Lowlight ‘s range?

Other data: I had previously hit consistently at 1000 yards with 8.5 mils using the same load/rifle and very close DA.

 

[Diver160651]

1- I’d be ultra concerned with how a bullet going your speed could produce a .6 mill drop at 300 regardless of the bullet’s BC
2- your numbers while lower than the solvers, are all over the place. Must be the gravitational thing..

 

[lte82]

1- I’d be ultra concerned with how a bullet going your speed could produce a .6 mill drop at 300 regardless of the bullet’s BCQUOTE]

Not really if the scope height is like 2.5", which is could be on that chassis. Also, a .390 g7 @ 2780 matches really well at all distances...

 

[Diver160651]

@lte82 Please show how you get a .6 drop at 300 using 25inhg at 2780fps with any bullet

 

[christopher.dow]

1- I’d be ultra concerned with how a bullet going your speed could produce a .6 mill drop at 300 regardless of the bullet’s BC
2- your numbers while lower than the solvers, are all over the place. Must be the gravitational thing..

1.) I consistently see 0.8 at 300 on my local range, where the DA runs +/- 300 ft based on weather, so 0.6 at 6400 isn’t crazy.
2.) That’s why I mentioned the rangefinder.

 

[lte82]

@lte82 Please show how you get a .6 drop at 300 using 25inhg at 2780fps with any bullet

No something is obviously way off there, and 400 seems a bit off too. It would need like 3500 fps lol. But from 500-1000 using a .390 g7 or the cdm it looks pretty close with the right velocity.

 

[Diver160651]

1.) I consistently see 0.8 at 300 on my local range, where the DA runs +/- 300 ft based on weather, so 0.6 at 6400 isn’t crazy.
2.) That’s why I mentioned the rangefinder.

it is crazy.. even at 24inHg Something, your tracking, shooter offset, groups, distance, something is wrong. Even .8 in the Bay Area is suspect at 300. Compounding the issue is dropping 2/10s going from 29 to 25inHg at 300.. should not be happening. Yes, you will see a huge difference but it takes more distance, the more distance the greater the effect of the thinner air.

 

[christopher.dow]

it is crazy.. even at 24inHg Something, your tracking, shooter offset, groups, distance, something is wrong. Even .8 in the Bay Area is suspect at 300. Compounding the issue is dropping 2/10s going from 29 to 25inHg at 300.. should not be happening. Yes, you will see a huge difference but it takes more distance, the more distance the greater the effect of the thinner air.

This discussion knocked loose the memory that I usually zero to 175gn Lapua Scenar-Ls, and at the class I was zeroed to Prime 175s. I didn't write that down in the ballistic calculator sheet because it's not one of the fields. That explains 0.8 in the Bay Area, as well. When I went back in to AB and put a 1.4" vertical offset (from my record of the 175gn Scenar-Ls vs. the 160gn Flatlines), I got this, which makes more sense:

The only thing that seems goofy now is 8.5 for 1000 yards. Looking at my notes, I wrote "~8.5" on the sheet, so I'm guessing I did that later and from memory, as 7.5 would be more in line with AB.

 

[Monk Medic]

Set your velocity to 2780 fps and see how that looks.

Fwiw I just recently tried a few custom curves and the data worked really well out to 1000 elevation wise. +/- .1 mil at pretty much every distance.

Also to get 7.3 elevation at 1000 with 2680 fps / 1200 DA you would need like a .480 g7. I would tend to believe your velocity is off before I believe your bc is that high. At 2770-2780 fps my trued g7 is .390 for the 300 scenar in my 338 norma.

Think that you may have nailed it!
That mv change makes the data match my acquired data curve very, very closely.
Thank you sir.

So, I’m going to postulate two things:

1) My Magnetospeed is inaccurate, despite using it in the past with my SIG SSG and getting data to match that rifle’s data. I did repeat it twice to confirm on the new AI gun.

2) After 185 rounds (since the ammo is the same factory Lapua .338 300 gr that I’ve used since the gun was new) then my rifle MV has increased from 2680 to 2780. Though this seems more likely, which seems more likely, is it possible?

Thoughts?

 

[lte82]

Think that you may have nailed it!
That mv change makes the data match my acquired data curve very, very closely.
Thank you sir.

So, I’m going to postulate two things:

1) My Magnetospeed is inaccurate, despite using it in the past with my SIG SSG and getting data to match that rifle’s data. I did repeat it twice to confirm on the new AI gun.

2) After 185 rounds (since the ammo is the same factory Lapua .338 300 gr that I’ve used since the gun was new) then my rifle MV has increased from 2680 to 2780. Though this seems more likely, which seems more likely, is it possible?

Thoughts?

Temp change + barrel speeding up in general seems a lot more likely to me. I have 1000's of rounds over my magnetospeed (it's a gen 2 I got years ago), and only once I've had my magnetospeed give me weird data. And it was because I shot the bayonet and it gave me bad velocities for a dozen rounds before stopped working.

 

[Bull81]

I’ve had the custom curves be drastically off just like your seeing with a certain bullets, with other bullets they will be spot on. I spoke with AB about this and at first they said it was me or my equipment, now they are checking into this a bit further to see what’s causing the custom curves to be off so much with certain bullets. The differences I am seeing almost mirrors yours.

 

[Monk Medic]

Temp change + barrel speeding up in general seems a lot more likely to me. I have 1000's of rounds over my magnetospeed (it's a gen 2 I got years ago), and only once I've had my magnetospeed give me weird data. And it was because I shot the bayonet and it gave me bad velocities for a dozen rounds before stopped working.

Quite possible the barrel has “sped up” now that its got some rounds down the pipe.
I’m going to chrono again this week and see what it records this time, will share the results of my testing.

 

[LastShot300]

Quite possible the barrel has “sped up” now that its got some rounds down the pipe.
I’m going to chrono again this week and see what it records this time, will share the results of my testing.

Now that you cleared the sky, can you post all the data used (MV, zero range, sight height, atmos, etc) and actual DOPE?

 

[Monk Medic]

Now that you cleared the sky, can you post all the data used (MV, zero range, sight height, atmos, etc) and actual DOPE?

Assuming you mean me?

Sure.

Rifle Data:
AI AXMC .338 Lapua 28” barrel
NF ATACR 7-35 F1
Sphur Mount 1.5”
Height above bore - 3”
Zeroed at 100 yards

Ammo:
Lapua Scenar 300 gr

Chrono:
Magnetospeed V3
Avg MV - 2671

Atmosphere:
1.2 KDA

Shooting position:
Prone from bipod

 

[_Windrider_]

Assuming you mean me?

Sure.

Rifle Data:
AI AXMC .338 Lapua 28” barrel
NF ATACR 7-35 F1
Sphur Mount 1.5”
Height above bore - 3”
Zeroed at 100 yards

Ammo:
Lapua Scenar 300 gr

Chrono:
Magnetospeed V3
Avg MV - 2671

Atmosphere:
1.2 KDA

Shooting position:
Prone from bipod

So was the temp you chrono’d at The same as when you were shooting? What were the environmetals when you were shooting?

 

[AbbyKatt]

Where/how does using the MV Calc table fit in to this truing discussion? Is using this function also a 'truing' exercise? Does anyone really use this feature?

And, if I understand it correctly, you're supposed to populate the table with muzzle velocities taken at about 30° apart. Since months can go by during this data collection time...if the barrel does 'speed up,' how does that effect the truing?

 

[lte82]

Where/how does using the MV Calc table fit in to this truing discussion? Is using this function also a 'truing' exercise? Does anyone really use this feature?

And, if I understand it correctly, you're supposed to populate the table with muzzle velocities taken at about 30° apart. Since months can go by during this data collection time...if the barrel does 'speed up,' how does that effect the truing?

If you true at 500 & 1000, there is usually only one combination of velocity and bc that will work for both distances. If you trued at say 2750 and it does up to 2800, you should be able to leave the bc alone and just bump your velocity up until your data matches.

 

[Monk Medic]

If you true at 500 & 1000, there is usually only one combination of velocity and bc that will work for both distances. If you trued at say 2750 and it does up to 2800, you should be able to leave the bc alone and just bump your velocity up until your data matches.

Thanks for the info, and yes, that does seem to be the case, once I tweaked it, the curve matched almost perfectly.

I'm going to redo the chrono this week, time permitting and capture a new set of data now that I have a couple hundred rounds down the pipe.

 

[DocUSMCRetired]

See if this helps:



Then check these out: http://www.appliedballisticsllc.com/Articles/BallisticCalibration.pdf

http://appliedballisticsllc.com/Articles/Firing Solution Check List.pdf

http://www.appliedballisticsllc.com/Articles/ChronographChapter.pdf

http://appliedballisticsllc.com/ballistics-educational-resources/articles/

 

[_Windrider_]

Where/how does using the MV Calc table fit in to this truing discussion? Is using this function also a 'truing' exercise? Does anyone really use this feature?

And, if I understand it correctly, you're supposed to populate the table with muzzle velocities taken at about 30° apart. Since months can go by during this data collection time...if the barrel does 'speed up,' how does that effect the truing?

i use it and it helps estimate drops at different temps where you havent collected data. the more temps/velocities you populate with it determines your average change in velocity per degree. it helps when you have data at say 90, 65, 40 and 30 when shooting at 55 for the first time. itll get you close if you dont have a chrono available, say if you are hunting. they say have at least 30 degrees betwen the high end and low end. of course that not possible all the time all at once, it could take two seasons to get there depending on where you live.

 

[Monk Medic]

See if this helps:



Then check these out: http://www.appliedballisticsllc.com/Articles/BallisticCalibration.pdf

http://appliedballisticsllc.com/Articles/Firing Solution Check List.pdf

http://www.appliedballisticsllc.com/Articles/ChronographChapter.pdf

http://appliedballisticsllc.com/ballistics-educational-resources/articles/

Thank you sir!

 

[Monk Medic]

Chrono Data - Recorded on a Magnetospeed V3

Got a chance to redo the data for the Accuracy International AXMC, and it proved @lte82 point, the MV had changed...by a lot.
Avg of 2665 fps back in March 1, 2018 to 2774 fps today, on May 1, 2018.

Total of 285 rounds down the pipe so far, before today's testing.
I also got the data on Lapua 250 gr rounds, the first time I had chonographed them,
some hot rounds there, avg was 3024 fps.

Thanks to those who took the time to get me feedback and wisdom on this rifle and ammo.
I'm really starting to fall in love with the gun, and develop a solid appreciation and understanding
of just what it is capable of.

Data Follows:

March 1, 2018
Temp: 50 degrees F
Ammo: Lapua Scenar 300 gr

Shot:
1 - 2665
2 - 2670
3 -2684
4 - 2703
5 - 2686

Max: 2703
Min: 2665
Avg: 2681
S-D: 14.9
=====================
May 1, 2018
Temp: 55 degrees F
Ammo: Lapua Scenar 300gr

Shot:
1 - 2769
2 - 2772
3 - 2770
4 - 2772
5 - 2778

Max: 2778
Min: 2769
Avg: 2774
S-D : 7.8
====================
May 1, 2018
Temp: 55 degrees F
Ammo: Lapua Scenar 250 gr

Shot:
1 - 3021
2 - 3039
3 - 3024
4 - 3018
5 - 3022

Max: 3039
Min: 3018
Ave: 3024
S-D: 8.2
================================

 

[lte82]

Chrono Data - Recorded on a Magnetospeed V3

Got a chance to redo the data for the SSG, and it proved @lte82 point, the MV had changed...by a lot.
Avg of 2665 fps back in March 1, 2018 to 2774 fps today, on May 1, 2018.

Total of 285 rounds down the pipe so far, before today's testing.
I also got the data on Lapua 250 gr rounds, the first time I had chonographed them,
some hot rounds there, avg was 3024 fps.

Thanks to those who took the time to get me feedback and wisdom on this rifle and ammo.
I'm really starting to fall in love with the gun, and develop a solid appreciation and understanding
of just what it is capable of.

Data Follows:

March 1, 2018
Temp: 50 degrees F
Ammo: Lapua Scenar 300 gr

Shot:
1 - 2665
2 - 2670
3 -2684
4 - 2703
5 - 2686

Max: 2703
Min: 2665
Avg: 2681
S-D: 14.9
=====================
May 1, 2018
Temp: 55 degrees F
Ammo: Lapua Scenar 300gr

Shot:
1 - 2769
2 - 2772
3 - 2770
4 - 2772
5 - 2778

Max: 2778
Min: 2769
Avg: 2774
S-D : 7.8
====================
May 1, 2018
Temp: 55 degrees F
Ammo: Lapua Scenar 250 gr

Shot:
1 - 3021
2 - 3039
3 - 3024
4 - 3018
5 - 3022

Max: 3039
Min: 3018
Ave: 3024
S-D: 8.2
================================

Sounds like you're on the right track!

 

[_Windrider_]

Chrono Data - Recorded on a Magnetospeed V3

Got a chance to redo the data for the Accuracy International AXMC, and it proved @lte82 point, the MV had changed...by a lot.
Avg of 2665 fps back in March 1, 2018 to 2774 fps today, on May 1, 2018.

Total of 285 rounds down the pipe so far, before today's testing.
I also got the data on Lapua 250 gr rounds, the first time I had chonographed them,
some hot rounds there, avg was 3024 fps.

Thanks to those who took the time to get me feedback and wisdom on this rifle and ammo.
I'm really starting to fall in love with the gun, and develop a solid appreciation and understanding
of just what it is capable of.

Data Follows:

March 1, 2018
Temp: 50 degrees F
Ammo: Lapua Scenar 300 gr

Shot:
1 - 2665
2 - 2670
3 -2684
4 - 2703
5 - 2686

Max: 2703
Min: 2665
Avg: 2681
S-D: 14.9
=====================
May 1, 2018
Temp: 55 degrees F
Ammo: Lapua Scenar 300gr

Shot:
1 - 2769
2 - 2772
3 - 2770
4 - 2772
5 - 2778

Max: 2778
Min: 2769
Avg: 2774
S-D : 7.8
====================
May 1, 2018
Temp: 55 degrees F
Ammo: Lapua Scenar 250 gr

Shot:
1 - 3021
2 - 3039
3 - 3024
4 - 3018
5 - 3022

Max: 3039
Min: 3018
Ave: 3024
S-D: 8.2
================================

Yeah that would change my initial response. I thought you had good MV data so that’s why insaid tweak the BC. I shoot a string at the start of every range session so I start my day on the right foot. Verify zero and get my MV at the same time. Then I start with my training

 

[Diver160651]

Yeah that would change my initial response. I thought you had good MV data so that’s why insaid tweak the BC. I shoot a string at the start of every range session so I start my day on the right foot. Verify zero and get my MV at the same time. Then I start with my training

How could anyone look at the .6mil drop and think anything was even close to being correct?

Guys, if you step back and understand that speed is short range. Then when the speed required makes zero sense, you can chase other errors.

With this logic, it should always become obvious when things are going sideways.

That alone should be the takeaway. Once you get the base level understood, every day shooting to the nuances of transonic tunning becomes more fruitful.

 

[_Windrider_]

How could anyone look at the .6mil drop and think anything was even close to being correct?

Guys, if you step back and understand that speed is short range. Then when the speed required makes zero sense, you can chase other errors.

With this logic, it should always become obvious when things are going sideways.

That alone should be the takeaway. Once you get the base level understood, every day shooting to the nuances of transonic tunning becomes more fruitful.

I assumed too much in the original post. im not trying to b eover hyper technical on this stuff and over analyze when people post stuff. simply put, if you have a good MV (which is essential) and your drops in real world are different than what the BC tells you by a wide margin and all other variable are accounted for, i dont care what range you are shooting at. if my MV is faster than whats published for the bullet, my BC is higher and vice versa if its slower. BC is velocity dependent. im not saying you adjust it from a .562-.765 and thats good, thats an extreme example. but tweaking it till you get close and then going to MV to compensate for the SD/chrono margin of error is the proper way to do it, IMHO and YMMV. like frank says many ways to get to 4.

When i start any range session, as i said above i verify zero and get my MV. i do this with a MS on the gun and a labradar at my side. id say i get good MV data so why on earth would i tweak that first? Especially when im shooting a 140ELD in my 6.5 at 2830 and the box gave me a published BC at 2710. my BC has to be higher.

We have talked about this on the phone at one point. i get what you are saying and im not saying you shouldnt tweak MV, im just saying do BC first and then very small MV tweaks to bring it in line, no more than 25 fps should be required..

 

[Diver160651]

I assumed too much in the original post. im not trying to b eover hyper technical on this stuff and over analyze when people post stuff. simply put, if you have a good MV (which is essential) and your drops in real world are different than what the BC tells you by a wide margin and all other variable are accounted for, i dont care what range you are shooting at. if my MV is faster than whats published for the bullet, my BC is higher and vice versa if its slower. BC is velocity dependent. im not saying you adjust it from a .562-.765 and thats good, thats an extreme example. but tweaking it till you get close and then going to MV to compensate for the SD/chrono margin of error is the proper way to do it, IMHO and YMMV. like frank says many ways to get to 4.

When i start any range session, as i said above i verify zero and get my MV. i do this with a MS on the gun and a labradar at my side. id say i get good MV data so why on earth would i tweak that first? Especially when im shooting a 140ELD in my 6.5 at 2830 and the box gave me a published BC at 2710. my BC has to be higher.

We have talked about this on the phone at one point. i get what you are saying and im not saying you shouldnt tweak MV, im just saying do BC first and then very small MV tweaks to bring it in line, no more than 25 fps should be required..

On a 6mm and up speed/BC class you are either misunderstanding Frank, or we are not comunication clearly (assuming all else such as range is squared away) to chase BC first inside 300 yards if you see a large point of impact departure from the prediction.

You’d be amazed just how much you could change the BC with zero point of impact shift at 200 or 300 yards on one of the above class bullets.

Once you have verified short range drops, then yes, tweak the BC first at further ranges.

 

[Christopher Rance]

What I teach is group/zero/ chronograph rifle then confirm at short-mid range (still inside supersonic) distance. If POA/POI is matching up, we then push out in distance, then tweak BC around transonic/subsonic distance if actual drops are not aligning with predicted drops. I factor in SD and the inherent precision of rifle before I start tweaking anything.

When using a Magnetto speed, AB CDM, and accurate inputs (scope height, zero range, SSF ect..) we usually see data spot on inside 800 meters with 175SMK out of M110’s.

 

[_Windrider_]

What I teach is group/zero/ chronograph rifle then confirm at short-mid range (still inside supersonic) distance. If POA/POI is matching up, we then push out in distance, then tweak BC around transonic/subsonic distance if actual drops are not aligning with predicted drops. I factor in SD and the inherent precision of rifle before I start tweaking anything.

When using a Magnetto speed, AB CDM, and accurate inputs (scope height, zero range, SSF ect..) we usually see data spot on inside 800 meters with 175SMK out of M110’s.

Totally off topic, but who makes the suppressor cover on the cover of SADJ Vol 10 no 2?

 

[Christopher Rance]

good question and I’ll inquire. Currently I use the Vertebrae band https://vertebrae.no/int/catalog/product/view/id/214/s/vertebrae-mirage-band-black/category/204/

I’ll find out and post when I get an answer.

Totally off topic, but who makes the suppressor cover on the cover of SADJ Vol 10 no 2?

View attachment 6900781

 

[_Windrider_]

good question and I’ll inquire. Currently I use the Vertebrae band https://vertebrae.no/int/catalog/product/view/id/214/s/vertebrae-mirage-band-black/category/204/

I’ll find out and post when I get an answer.

Appreciate it. I’ve had that issue sitting on my desk since it came. Been trying to find the answer.

 

[LastShot300]

I finally ran the AB numbers against what @TacticalDillhole and I collected in Ft Morgan:

Warner Flatline .308 160gn
BC: .589 (G1)/.294 (G7) from Hornady Doppler
MV: 2852
DA: 6000
SP: 25.3
T: 67.6
H: 23

Distance Measured AB JBM Trasol Hornady
200 0.3 0.3 0.4 0.4 0.4
300 0.6 1.0 1.1 1.0 1.1 <- Huh?
400 1.1 1.7 1.8 1.7 1.8
500 1.7 2.5 2.6 2.5 2.6
600 2.8 3.4 3.5 3.4 3.5
710 3.9 4.4 4.4 4.3 4.5 <- actually 711
800 5.0 5.4 5.4 5.3 5.6
900 6.0 6.6 6.5 6.4 6.8
1000 8.5 7.8 7.7 7.6 8.2

Clearly, Hornady is closest. I haven’t been able to get the BC to true any of these. It’s possible we had the distances wrong, but we’d been shooting on that range for two days already, and I think @TacticalDillhole was using my range finder. He was also using my spotting scope with mil reticle, so he was giving me good corrections.

So did the time-traveling Chinese put a gravitational anomaly on @Lowlight ‘s range?

Other data: I had previously hit consistently at 1000 yards with 8.5 mils using the same load/rifle and very close DA.

I know, I'm late to the party but while perusing around the forum I found this post, curiosity led to me check the data and the BCs
So, you say Warner but your data is from Hornady? If I run your data with what is published by Warner I get this at 1000

JBM 8.1 and Trasol 8.3 (in reality I used CB but I guess the results should be the same)

So it looks like your BC source is not quite right which clearly explains the difference between your observed dope and the programs. What made me to check was the distance, in my experience not having a good or close match at 1000 is usually not happening unless the inputs are not right.