Ballistics Help?????

[krktractor]

ok guys. I have 2 well know ballistics apps and have a issue. I enter my info and find myself too high everytime. the farther the distance the worst the problem gets. I know these facts for sure. I have my muzzle velocity, bc1 or bc7 whichever I choose to use , bullet lenght, tempature and atmosphere correct. Here is where I think my issue is.

Sight height. I'm sure this means center line of scope to rifle bore. if I'm wrong please correct me.

Zero height. ???? not sure.

Zero offset. ???? not sure.

If someone who knows would gladly school me here I would appricieate it. thanks for any help.

 

[CatShooter]

ok guys. I have 2 well know ballistics apps and have a issue. I enter my info and find myself too high everytime. the farther the distance the worst the problem gets. I know these facts for sure. I have my muzzle velocity, bc1 or bc7 whichever I choose to use , bullet length, temperature and atmosphere correct. Here is where I think my issue is.

Sight height. I'm sure this means center line of scope to rifle bore. if I'm wrong please correct me.

Zero height. ???? not sure.

Zero offset. ???? not sure.

If someone who knows would gladly school me here I would appreciate it. thanks for any help.

More information would help... like what bullet, what software, etc...

... but scope height is from the center like to the center of the bore - typically 1.75" for normal rifles and scope rigs.

 

[LitLBoy]

Measure your bore center line to scope center line that will be your scope height.
"off set" is your chose --- pick the distance you want for your ZERO (100 - 200 - 300 yds) you pick and then select "0" off set at that distance. Then select max. range, unless I'm missing something in your question you should be good to go. When you figure a new traj. table post it along with all your input information. The guys here can tell pretty quick if the numbers are right

 

[Lapua40X]

From another perspective - I see that you have the BC data. Problem is that published BC data is often exaggerated. If you play with the BC data in your app, entering variations of BC that bring the data results in line with your actual target results and then use that BC data for the next iteration you may find that you get more useful outputs.

 

[Nomad47]

If your POI is always higher than your POA, your scope could be MOA and your chart IPHY (inches per hundred yards.
Zero your scope for 100 yards, then turn the turret up to '10' and shoot a 3 shot group. If the bullets impact 10" high, then your scope is calibrated in inches per hundred yards. And if the impacts are 10.47" high, then your scope is calibrated in MOA.

Or maybe your chrony is lying to you and your velocity is higher than what the chronograph says.

 

[CatShooter]

Something else to consider. If you have a 20 moa rail and adjust for a 100 yard zero, would the scope height be measured to the center of the scope tube or to the center of the reticle that now sits higher in the tube? I've always wondered if this has any effect.

You're being anal... and those measurements are in the thousandths of an inch.

The measurement is from the center of the scope tube to the center of the bore... nothing else.

1/8ths of an inch are more than close enough.

 

[Grimstod]

You can never be to anal about ballistics ;D but if you really want to get technical measure both front and back, ad them together then divide by two. This will give you the center of the scope.


A tilted scope should not really be an issue unless your shooting 2000yards. I do not worry about scope rails with MOA built into them. I just measure the front one and call it good.

 

[lawrence97]

Best method is to get proper dope for the distances you will be shooting at using real world data. The ballistics apps are only as good as the data you input. I only use them to get a ballpark figure because there are so many variables that can affect the data they put out.
I usually adjust the muzzle velocity field on the app until it coincides with my real world drop. My app usually puts me higher just as yours has done and I fine tune from there with muzzle velocity figures.

Also, how accurate is the velocity figure you are inputting on the app? Ambient temp, altitude, barrel temp, etc

 

[krktractor]

thanks for all the replies. my questions were answered and I have gotten it a little closer. by the way I'm shooting a 6.5x47 with 140 berger hybrids at 2900 I adjusted the BC and sight height and got it ok. when I shot at 350 yards app shows 4.76 moa up and I was at 4 moa. I know it's not much but when I stretch out to 1000 I miss a 12x12 plate , and that is even holding off all the way at the bottom. this may be two picky but if the app is going to ask for all this info I would expect it to be a little closer. I have the shooter app and the ballistics app also. I will give them one thing I got the same info from both apps, so I guess it's my error. at least one person has had the same problem. thanks to all that took time to post they're opinions and knowledge

 

[Jeremy(WI)]

A pic of the shooter app options

 

[ebb]

I've had these issues before, for me its usually BC. The advertised BC is much better than the actual BC.

 

[timeout]

I've had these issues before, for me its usually BC. The advertised BC is much better than the actual BC.

For what it's worth, Berger reccomends using their G7 BC to get closest info outcome. Only ballisics calculator that I have used so far is JBM on my PC. I have a dumb phone so until that changes I probably won't experience the others.

 

[ALppc]

Bryan Litz has a 3 dvd set that will explain all of this in detail. Its called "Putting Rounds on Target"
It can be purchased here. http://store.appliedballisticsllc.com/

A word of advice about the DVD, don't skip any steps they are all important.

Al Barnhart
Michigan F-TR team