Bullet impact vs. StrelokPro data

kooJoe · Feb 11, 2019

Good morning, I can’t say that I have spent any decent amount of time on this website, so please forgive if this topic has been covered.

I have been shooting crop damage for ten years. I have access to many private ranges beyond 1000yds on the eastern shore. I am by no means a professional, but I am light years from being green. We continually kill deer at ranges beyond 800 yds. Point being I have gotten very comfortable with my rifle. My question;

Has anyone ever had issues Getting StrelokPro app to match their true bullet impact?

In my case I have to fudge my zero on the program in order to have the program tables match my field results. In other words, my rifle is truly zeroed for 200 yds, but I have to lie to the program and say it’s 245 yd zero in order to have bullet impacts line up with program curve. I realize how insane this sounds, but this is what works for me.

My rifle is a .308, I have become lazy and shoot factory ELD Match 155’s (surprisingly consistent). Average muzzle velocity is 2812... this is confirmed via crono.

I do use a tapered 20 MOA base. This rifle groups less than 6 inches at 1000yds.

smdub · Feb 11, 2019

Likely biggest cause (if you've checked everything else) is wrong BC. Tweak it and see if you can get a match.

kooJoe · Feb 11, 2019

Tried re adjusting BC on app. Tried different g1 and or g7 values... no luck.

I’ve tried inputting faster velocities while using my true 200 yd zero value, and can get drops to come within an inch or two at 400 and 600 yds, but way off at 1000.

I realize I’m not shooting paper at competitions, and again I get by with my manipulated ballistic app, but I’m sitting here scratching my head on this one.

erwos · Feb 11, 2019

Did you set altitude and temperature variables?

smdub · Feb 11, 2019

Post your data here (distances vs drop/holdover needed)

Qbeam · Feb 11, 2019

Did you select the actual cartridge or one of the formulas? What brand is ELD?

Q

I have Strelok Pro.

davsco · Feb 11, 2019

do you have a stepped/banded bc in there, some bullet companies give you bc's at various speeds that you can enter into your ballistics program?

also this thread and site may help:
https://forum.snipershide.com/threads/truing-mv-vs-bc.6891826/

Pinecone · Feb 11, 2019

Have you tried different ballistic programs?

JBM is free to use online, and the same engine is used in Ballistic and Ballistic AE.

As was mentioned, are you properly entering temp and air pressure?

Speed3 · Feb 11, 2019

Is the scope above bore correct? That is another that many people overlook

Yoshi · Feb 11, 2019

That's odd. Strelok has always been on the money for me. Especially with my .308. Did you check to make sure your "zero" is listed as "200" in the app?

Qbeam · Feb 11, 2019

Are you shooting from an elevated position?

Q

kooJoe · Feb 11, 2019

Hey guys, thank you all for your thoughtful comments and suggestions. Forgive me for taking this long to respond, it was a rough Monday at work.
Anyhow, i have reviewed all of my input variables. They all look good to me.

I must stress that I have 100% confidence in the solutions that the app gives me (while inputting my fake zero). I am just hell bent on figuring out why i have to cheat the program.

Let me share additional details;
1:12 twist, .308, 155gn Hornady ELD Match, g7 BC .232, average mv of 2813 (5 shots) zeroing weather 37 degrees, pressure 30.6, humidity 38%, altitude 39', shooting north to south, zero shooting angle to target, following drops recorded on same day of zeroing.... TRUE bullet drops; 200 yd zero (all bullet holes touching), 400 yd drop of 4.5MOA , 600 yd drop of 11.5 MOA, 1000 yd drop of 34.5MOA....... Strelok program using 200 yard zero and all variables mentioned above calls for 5.5MOA for 400 (hit 1MOA high), 13MOA for 600 (hit 1.5MOA high), and 35.5MOA at 1000 (hit 1MOA high).

The next decent day of shooting, I am going to get back to basics. Double check that the scope is tracking true on elevation, then shoot box at various distances confirming drops..... I need to be careful not to mind f*%k myself on this. Thank you guys!

Qbeam · Feb 11, 2019

kooJoe said:
Hey guys, thank you all for your thoughtful comments and suggestions. Forgive me for taking this long to respond, it was a rough Monday at work.
Anyhow, i have reviewed all of my input variables. They all look good to me.

I must stress that I have 100% confidence in the solutions that the app gives me (while inputting my fake zero). I am just hell bent on figuring out why i have to cheat the program.

Let me share additional details;
1:12 twist, .308, 155gn Hornady ELD Match, g7 BC .232, average mv of 2813 (5 shots) zeroing weather 37 degrees, pressure 30.6, humidity 38%, altitude 39', shooting north to south, zero shooting angle to target, following drops recorded on same day of zeroing.... TRUE bullet drops; 200 yd zero (all bullet holes touching), 400 yd drop of 4.5MOA , 600 yd drop of 11.5 MOA, 1000 yd drop of 34.5MOA....... Strelok program using 200 yard zero and all variables mentioned above calls for 5.5MOA for 400 (hit 1MOA high), 13MOA for 600 (hit 1.5MOA high), and 35.5MOA at 1000 (hit 1MOA high).

The next decent day of shooting, I am going to get back to basics. Double check that the scope is tracking true on elevation, then shoot box at various distances confirming drops..... I need to be careful not to mind f*%k myself on this. Thank you guys!

This is using the cartridge from the cartridge database, and adjusting the other variables?

Q

ToolAA · Feb 11, 2019

I just ran your data in Ballistic AE and the results are very close to Strelock.

danb · Feb 12, 2019

When I use the given data in post #12 in shooterscalculator: http://www.shooterscalculator.com/b...bf;Vel[x+y]~ft/s&lbl=&submitst=+Create+Chart+

I get closer to the true drop. But I used a 2.5" scope height. About .75 MOA off at 400 yds , 1 MOA at 600, and 1000 yards is spot on. I dont see where you listed your scope height. Small changes in measurements like in scope height of .25 will change the 600 yd by about .15 MOA and add up. Also, small changes in shooting angle are going to matter too. The weather (relative humidity, pressure, etc,) 600 yds downrange may not be the same as at your ear.

These ballistic calculators should only be considered approximations. Solving the aerodynamic equations is very complicated - and there are a lot of approximations that add up.

I would not substitute the calculator for real world experience. These are not as accurate as people think that they are. I think that the good news is that it looks to me as though you are off about 1-1.5 MOA at 600 yds, which is about 6x better than most people can even shoot at 100yds on a good day.

I think your rifles accuracy is way beyond the ability of an inexpensive ballistics program. In fact, your rifle has the kind of accuracy they use to calibrate ballistics programs.

jcutonilli · Feb 12, 2019

kooJoe said:
Hey guys, thank you all for your thoughtful comments and suggestions. Forgive me for taking this long to respond, it was a rough Monday at work.
Anyhow, i have reviewed all of my input variables. They all look good to me.

I must stress that I have 100% confidence in the solutions that the app gives me (while inputting my fake zero). I am just hell bent on figuring out why i have to cheat the program.

Let me share additional details;
1:12 twist, .308, 155gn Hornady ELD Match, g7 BC .232, average mv of 2813 (5 shots) zeroing weather 37 degrees, pressure 30.6, humidity 38%, altitude 39', shooting north to south, zero shooting angle to target, following drops recorded on same day of zeroing.... TRUE bullet drops; 200 yd zero (all bullet holes touching), 400 yd drop of 4.5MOA , 600 yd drop of 11.5 MOA, 1000 yd drop of 34.5MOA....... Strelok program using 200 yard zero and all variables mentioned above calls for 5.5MOA for 400 (hit 1MOA high), 13MOA for 600 (hit 1.5MOA high), and 35.5MOA at 1000 (hit 1MOA high).

The next decent day of shooting, I am going to get back to basics. Double check that the scope is tracking true on elevation, then shoot box at various distances confirming drops..... I need to be careful not to mind f*%k myself on this. Thank you guys!

You do not specify what your sight height is and do not account for the fact that you have a 20 MOA base. The base creates a different angle, which is not accounted for.

Pinecone · Feb 12, 2019

Base angle makes no difference. It just puts the zero point at a different part of the adjustment range.

The sight height is a VERY important measurement to get right.

Speed3 · Feb 12, 2019

Pinecone said:
Base angle makes no difference. It just puts the zero point at a different part of the adjustment range.

The sight height is a VERY important measurement to get right.

This... I'm betting its scope height above bore issue.

davsco · Feb 12, 2019

in my one program, going from 1.5 scope height to 2.5 changed 1000 yd poi by one moa.

Speed3 · Feb 12, 2019

davsco said:
in my one program, going from 1.5 scope height to 2.5 changed 1000 yd poi by one moa.

Which is about what he is off at each distance. Now im not sure that his scope height is off a full inch though, that would be huge. Has to be something else going on

Bullet impact vs. StrelokPro data

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