I got a chance to finally shoot 1,000 yard. The only ranges in my area are 100 yards. I'm using a .308 PAI rifle with a USO T-PAL with hand rolled ammo - 175 grain Sierra MatchKing, 45.3 grains of Varget, Winchester brass, and CCI Benchrest primers going 2750 fps. Using iPhone Ballistic it said the calculated come up would be 9.47 mrad for 1,000 yards. After walking in a few rounds the actual come up was 10.3 mrad. Is there a way or a program to covert the calculated come ups according to the actual come up for all ranges (50 yards to 1200 yards)? I do not have the range/capability to shoot at each distance to correct the ballistic table.
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Correcting Ballistics Table?????
- Thread starter exd3686
- Start date
Re: Correcting Ballistics Table?????
Not to sound overly simplistic or snotty. But you have something wrong. Enviro is wrong, velocity is wrong, BC is wrong or shooting position is wrong or a combination of the above.
Here is a link to an EXCELLENT article from Lindy here on the hide.
http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/Programs/
Not to sound overly simplistic or snotty. But you have something wrong. Enviro is wrong, velocity is wrong, BC is wrong or shooting position is wrong or a combination of the above.
Here is a link to an EXCELLENT article from Lindy here on the hide.
http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/Programs/
Re: Correcting Ballistics Table?????
Believe me. I'll take any advice willing to be shared....being a big time newbie. I worked up an accurate load at 100 yards (0.25 group). Did the chrony for a group of over 20 rounds and took the average....2750 fps. Used the Ballistic app on iPhone to record the zero climate conditions. Used Ballistic app to enter in the fps, sight height, drag model based on Ballistic app for the Sierra 175 grain. When at the competition, I adjusted the current atmosphere conditions using the iPhone Ballistic app and came up with the same readings for 1,000 yards....9.47 mrad but still needed 10.3 mrad to get centered on target. Any help is more than welcome!!!!
Believe me. I'll take any advice willing to be shared....being a big time newbie. I worked up an accurate load at 100 yards (0.25 group). Did the chrony for a group of over 20 rounds and took the average....2750 fps. Used the Ballistic app on iPhone to record the zero climate conditions. Used Ballistic app to enter in the fps, sight height, drag model based on Ballistic app for the Sierra 175 grain. When at the competition, I adjusted the current atmosphere conditions using the iPhone Ballistic app and came up with the same readings for 1,000 yards....9.47 mrad but still needed 10.3 mrad to get centered on target. Any help is more than welcome!!!!
Re: Correcting Ballistics Table?????
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: exd3686</div><div class="ubbcode-body">I used the iPhone Ballistic program for the zero conditions as well as the weather conditions at time of firing. </div></div>
Where did you get the "weather conditions at the time of firing"? From a Kestrel, or similar, at the range - or did you use the iPhone to get the weather details from within Ballistic? I ask this since if it was with Ballistic it is just getting weather from the closest weather station, which could be a long way, and very different from the range you were shooting at.
bill
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: exd3686</div><div class="ubbcode-body">I used the iPhone Ballistic program for the zero conditions as well as the weather conditions at time of firing. </div></div>
Where did you get the "weather conditions at the time of firing"? From a Kestrel, or similar, at the range - or did you use the iPhone to get the weather details from within Ballistic? I ask this since if it was with Ballistic it is just getting weather from the closest weather station, which could be a long way, and very different from the range you were shooting at.
bill
Re: Correcting Ballistics Table?????
Billf
Very good point. I was using the iPhone Ballistic app to pull the local weather conditions. My zero weather info was 66 degrees F, 44% humidity, 29.06Hg pressure. My firing weather info was 72 degrees F, 53% humidity, 29.26 Hg pressure. The slight differences did not change the original 1000 yard setting of 9.47 mrad. Any ideas? I'm not so worried about the inaccuracy but would like to correct the calculated come ups for the actual come ups!
Billf
Very good point. I was using the iPhone Ballistic app to pull the local weather conditions. My zero weather info was 66 degrees F, 44% humidity, 29.06Hg pressure. My firing weather info was 72 degrees F, 53% humidity, 29.26 Hg pressure. The slight differences did not change the original 1000 yard setting of 9.47 mrad. Any ideas? I'm not so worried about the inaccuracy but would like to correct the calculated come ups for the actual come ups!
Re: Correcting Ballistics Table?????
According to Bryan Litz (I highly recommend his book) the BC at 2750fps should be 0.241. I am not sure how much of a difference that will make but your 0.252 corresponds to a velocity of 1500fps.
Tis worth a try...
According to Bryan Litz (I highly recommend his book) the BC at 2750fps should be 0.241. I am not sure how much of a difference that will make but your 0.252 corresponds to a velocity of 1500fps.
Tis worth a try...
Re: Correcting Ballistics Table?????
I've got two ideas that are likely reasons for your discrepancy.
1) What kind of chronograph did you use to measure the velocity? Cheap chronographs (like the shooting chrony) can give you errors on the average velocity.
2) Have you verified your scope adjustment? I know the USO is an expensive optic, but it doesn't guarantee it's giving you 1:1 adjustments. I recommend verifying this before worrying about the ballistics. Shoot a group at the bottom of a tall target at 100 yards with your 100 yard zero, then adjust up 10 MILS and shoot another group. Measure the distance between the groups to make sure the scope is moving as much as you think it is.
One more thing; are you sure the target which required 10.2 MILS is exactly 1000 yards? If it were 1010 or 1020 that could account for your extra needed elevation.
Just some ideas,
-Bryan
I've got two ideas that are likely reasons for your discrepancy.
1) What kind of chronograph did you use to measure the velocity? Cheap chronographs (like the shooting chrony) can give you errors on the average velocity.
2) Have you verified your scope adjustment? I know the USO is an expensive optic, but it doesn't guarantee it's giving you 1:1 adjustments. I recommend verifying this before worrying about the ballistics. Shoot a group at the bottom of a tall target at 100 yards with your 100 yard zero, then adjust up 10 MILS and shoot another group. Measure the distance between the groups to make sure the scope is moving as much as you think it is.
One more thing; are you sure the target which required 10.2 MILS is exactly 1000 yards? If it were 1010 or 1020 that could account for your extra needed elevation.
Just some ideas,
-Bryan
Re: Correcting Ballistics Table?????
exd3686, QuickTarget, which is part of the QuickLoad software, can calculate BC based on MV and drop at any two distances. Drop at your zero distance should be -- surprise! -- zero. And you can calculate drop @1000 yards from your come-up. <span style="text-decoration: underline">If</span> your calculated BC differs from what Sierra says, this could give you the data to correct your come-ups.
Also, as for what Bryan wrote, I have a Shooting Chrony and a CED chrono and I don't trust the calculations from either of them. I always record the MV from each shot in my range log, then keypunch the numbers into a spreadsheet when I get home.
exd3686, QuickTarget, which is part of the QuickLoad software, can calculate BC based on MV and drop at any two distances. Drop at your zero distance should be -- surprise! -- zero. And you can calculate drop @1000 yards from your come-up. <span style="text-decoration: underline">If</span> your calculated BC differs from what Sierra says, this could give you the data to correct your come-ups.
Also, as for what Bryan wrote, I have a Shooting Chrony and a CED chrono and I don't trust the calculations from either of them. I always record the MV from each shot in my range log, then keypunch the numbers into a spreadsheet when I get home.
Re: Correcting Ballistics Table?????
exd3686 you have some solid info here... as you can see, there are so many variables to take into consideration, slipping up on just one can easily push you off target at 1000.
exd3686 you have some solid info here... as you can see, there are so many variables to take into consideration, slipping up on just one can easily push you off target at 1000.
Re: Correcting Ballistics Table?????
Using Sierra's BC instead of Litz' would account for .3-.4 mRad alone. The rest I'd guess are more to do with imprecise atmospheric conditions - both when zeroing and that day. One thing to know about Ballistic:
If you were able to zero @ 500 yards or greater, you would actually see a minute difference in your zero drop when Current Atmosphere differs from the Zero Atmosphere (e.g. from 0.0" to 0.2")
So if you zero @ 100 yards/meters, like many of us do (for good reason), you won't account for this variation at long distances. It could result in another .1 mRad @ 1000 yards. From my discussions with the author, this is just the way Ballistic works. I don't worry about it because it has very little effect. I'd really try to get precise conditions for your location when zeroing and again when shooting.
Using Sierra's BC instead of Litz' would account for .3-.4 mRad alone. The rest I'd guess are more to do with imprecise atmospheric conditions - both when zeroing and that day. One thing to know about Ballistic:
If you were able to zero @ 500 yards or greater, you would actually see a minute difference in your zero drop when Current Atmosphere differs from the Zero Atmosphere (e.g. from 0.0" to 0.2")
So if you zero @ 100 yards/meters, like many of us do (for good reason), you won't account for this variation at long distances. It could result in another .1 mRad @ 1000 yards. From my discussions with the author, this is just the way Ballistic works. I don't worry about it because it has very little effect. I'd really try to get precise conditions for your location when zeroing and again when shooting.
Re: Correcting Ballistics Table?????
Thanks everyone for your input. I will look into each suggestion and see what works. Problem is I only get to shoot at 1000 once a year. Only 100 yrds around here.
I was using a cheap shooting chrony but recorded each MV and calculated the average myself.
I'll try out the 100 yrd. zero and come up 10mrad and mesure the difference to check the scopes accuracy.
I'll also invest in a good Kestral for accurate weather conditions. My older Leica 1200 indicated 1009 yrds.
I really like this load but want an accurate table for all ranges between 50 yrds and 1000 yrds so I can concentrate on the other shooting factors like that damn wind. To be completely honest, I was just happy to hit something at 1000. I got several X's and a bunch of 9s and 10s so I'm quite happy overall.
Thanks for the ideas!
Thanks everyone for your input. I will look into each suggestion and see what works. Problem is I only get to shoot at 1000 once a year. Only 100 yrds around here.
I was using a cheap shooting chrony but recorded each MV and calculated the average myself.
I'll try out the 100 yrd. zero and come up 10mrad and mesure the difference to check the scopes accuracy.
I'll also invest in a good Kestral for accurate weather conditions. My older Leica 1200 indicated 1009 yrds.
I really like this load but want an accurate table for all ranges between 50 yrds and 1000 yrds so I can concentrate on the other shooting factors like that damn wind. To be completely honest, I was just happy to hit something at 1000. I got several X's and a bunch of 9s and 10s so I'm quite happy overall.
Thanks for the ideas!
Re: Correcting Ballistics Table?????
I agree with Bryan regarding verification of your scopes actual correction per click. Just because you have a $$$$$ scope does not guarantee that it adjust as advertised. I verify every long range scope I use.
I have targets I made up to do so! I set the target at exactly 100yds (Verified with tape and laser). Then I fire 5 rounds at the aim point and make sure I am zeroed. I then run the scope up 10moa fire, 20moa fire, and 30moa. Then check you target.
Also, I always use a plumb line to make sure my vertical line on my target is 90deg vertical. This will also ensure your scope tracks vertically and that you scope is mounted level. finally a scope bubble level helps on your rifle to ensure you are not firing from a canted position.
I agree with Bryan regarding verification of your scopes actual correction per click. Just because you have a $$$$$ scope does not guarantee that it adjust as advertised. I verify every long range scope I use.
I have targets I made up to do so! I set the target at exactly 100yds (Verified with tape and laser). Then I fire 5 rounds at the aim point and make sure I am zeroed. I then run the scope up 10moa fire, 20moa fire, and 30moa. Then check you target.
Also, I always use a plumb line to make sure my vertical line on my target is 90deg vertical. This will also ensure your scope tracks vertically and that you scope is mounted level. finally a scope bubble level helps on your rifle to ensure you are not firing from a canted position.
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