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bullet drop - CPT.CRAZY - 05-11-2013
I'm going to my first F class shoot soon I want to use my 6.5, help out with a starting point for drop shooting 123 amax at 2660 fps my drop from a 100 yrd zero to 600yrds should be how much in MOA?? Thanks in advance for the help.
bullet drop - bwaites - 05-11-2013
CPT.CRAZY Wrote:I'm going to my first F class shoot soon I want to use my 6.5, help out with a starting point for drop shooting 123 amax at 2660 fps my drop from a 100 yrd zero to 600yrds should be how much in MOA?? Thanks in advance for the help.
CPT, use this ballistic calculator, and print out the results:
http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi
The best answer to your question is to work through the information yourself. If you can't figure it out, come back and ask more questions, and we'll help!
bullet drop - gonzaga - 05-17-2013
I come up with 15.3 MOA at 600. But I punched that your sight in is at 1.5.
That should be pretty close.
Elevation would vary your results as well
bullet drop - Nukes - 05-17-2013
Assuming good zero, good chrono, good atmospheric, and using Litz's BC data for the 123gr Scenar, any ideas why the calculated ballistics tables would be way off (errors of 0.5 @ 200yds, 0.6 @ 500 yds from observed values)? The observed drops are considerably less than predicted by the tables.
Shooter, Kestrel Horus, and the online link above all agree in their calculations, but are 0.5-0.6 mil worse than observed.
With .308 and .338LM the tables have agreed within 0.0-0.2 of observed out to 800 yds.
bullet drop - LR1955 - 05-18-2013
Nukes Wrote:Assuming good zero, good chrono, good atmospheric, and using Litz's BC data for the 123gr Scenar, any ideas why the calculated ballistics tables would be way off (errors of 0.5 @ 200yds, 0.6 @ 500 yds from observed values)? The observed drops are considerably less than predicted by the tables.
Shooter, Kestrel Horus, and the online link above all agree in their calculations, but are 0.5-0.6 mil worse than observed.
With .308 and .338LM the tables have agreed within 0.0-0.2 of observed out to 800 yds.
Nukes:
If your ballistics program is accurate to under 1/2 mil @ 600, it is fine. You would have a real hard time trying to figure out what variables are involved and a harder time trying to figure out how much of that .6 M they account for.
You would also have to shoot a lot of ammo under identical environmental conditions to get a statistical sample that has any meaning.
At the longer ranges, seeing becomes an issue with dust, humidity, and other natural obscurants hindering a shooters ability to see well enough for perfect precision. If he is using hold overs, his accuracy lessens. Most of the time he has not measured the distance well enough and unless he is shooting on paper where he can measure shot groups accurately, he can be way off from something that is published. Most shooters have big problems calling their shots and without good, accurate, shot calls, it is almost impossible to figure out what is going on when faced with about any shooting issue.
Many guys shoot on steel and this must be the least accurate way of figuring out a zero. Unless you shoot through paper at a exact distance, and then measure a good statistical sample, you can't be sure what, if anything, is wrong.
Finally, there are a great number of ballistics programs out there that all give slightly different solutions. And, they tend to follow range bands with 500 or 600 being a dividing line with one program for the shorter distances and another for the longer ones.
I wouldn't get hung up over someones ballistics program not being perfect. Use them to get you close and then get your own data.
LR1955
bullet drop - CPT.CRAZY - 05-18-2013
Thanks for the help guys, I used the Strelok app on my phone and came up with 14.7 MOA that was close enough to get me on paper and zero from there.
bullet drop - Nukes - 05-19-2013
LR1955 Wrote:Nukes:
If your ballistics program is accurate to under 1/2 mil @ 600, it is fine. You would have a real hard time trying to figure out what variables are involved and a harder time trying to figure out how much of that .6 M they account for.
You would also have to shoot a lot of ammo under identical environmental conditions to get a statistical sample that has any meaning.
At the longer ranges, seeing becomes an issue with dust, humidity, and other natural obscurants hindering a shooters ability to see well enough for perfect precision. If he is using hold overs, his accuracy lessens. Most of the time he has not measured the distance well enough and unless he is shooting on paper where he can measure shot groups accurately, he can be way off from something that is published. Most shooters have big problems calling their shots and without good, accurate, shot calls, it is almost impossible to figure out what is going on when faced with about any shooting issue.
Many guys shoot on steel and this must be the least accurate way of figuring out a zero. Unless you shoot through paper at a exact distance, and then measure a good statistical sample, you can't be sure what, if anything, is wrong.
Finally, there are a great number of ballistics programs out there that all give slightly different solutions. And, they tend to follow range bands with 500 or 600 being a dividing line with one program for the shorter distances and another for the longer ones.
I wouldn't get hung up over someones ballistics program not being perfect. Use them to get you close and then get your own data.
LR1955
Thank you.
Maybe I have been spoiled to this point by having the programs agree with each other and also agree with observations within 0.0-0.2 mil.
Thanks again.
bullet drop - LRRPF52 - 05-19-2013
CPT.CRAZY,
If you want your sighter to be closer on the day of the match, make sure you know your zero weather conditions, and then plug in the conditions for the morning of the match. Barometric pressure and temperature will be your biggest factors that will change the drop enough to be noticeable.
bullet drop - Nukes - 05-23-2013
A more accurate measurement of scope height cut the calculated/observed disparity in half.
bullet drop - Jon A - 05-24-2013
You havent been spoiled at all. Any modern ballistics program will easily be accurate to within .1 Mil at 600 yds when used properly. Youre doing the right thing in figuring out the input errors which are causing the output errors.
Since you notice error at relatively close range that gives some indications as to what the input error is. Im guessing you nailed it with the sight height over bore measurement. Has the error at 200 yds now pretty much disappeared? If not look mostely at #3 below.
Errors in the 300-600 range are still relatively close which eliminates BC error as the primary cause. The three biggies to look for in this range are:
Velocity. Re-chrongraph, double check with a different chronograph if possible.
Scope tracking. Until youve carefully measured your scope clicks, you really have no idea how much compensation youre dialing. Very few scopes are so close to dead nuts on that you dont need compensation in the program.
Zeroing error. This may sound dumb, but I think it happens a lot more than people realize. Many will zero at 100 gently holding the rifle coddled in sandbags from the bench. Then theyll go lay in the dirt, firmly holding the rifle on a bipod to shoot long range and assume ballistic errors are why theyre missing when really theyve changed the natural POI of the rifle with the different hold. ARs are a lot more sensitive to this than bolt rifles in my experience. Pick a hold and stick with it for everything.
Those are the most likely off the top of my head for your remaining error.