Shot at 808 yrds and need help........

[bigbuck]

Okay I use the NF software with a dell pocket PC.

Distance was 808 as mentioned in the title.

field conditions from my kestrel 3500 is as follows.

Temp....... 72.5 degrees
R.H.......... 73.6
Baro .......29.13
Alevation .742

Exbol said I should dial 15 MOA up. fired one shot
Drove out to the target and ended up 5.410 inches low.

Now my question is this what should the correction( Target Validation) in MOA be to get me dead center at 808 ? New MV ?

If you need more info then let me know .

Thanks for looking.

 

[royinidaho]

Your impact was about 0.67 MOA low.

Try some intermediate distances and note the trend before making any further decisions.

You noted both Elevation and barometric pressure. Only one of these inputs should be necessary.

Keep us posted on your progress

 

[Scot E]

I am not sure how accurate your gun is and how good of a shot you are and how confident you are in a 1 shot group but I would suggest at least shooting a group of 3 to find the center of your group. At 800 yards a 1/2 MOA gun will be shooting 4 inch groups. So your shot is only about an inch outside of that. Now if they all are shooting low then an adjustment needs to be made.

I can't run any numbers for you based off the info you gave so I am not going to be much help there. If you want comparison drops from another program you need to post muzzle velocity, bullet weight, BC, incline/decline. I agree with Roy most calculators don't like pressure and altitude both. It messes things up. I use station pressure only and eliminate altitude as the pressure accounts for it.

HTH,

Scot E.

 

[Broz]

You might want to consider shooting a group instead of 1 shot. Then take the center of the group in eevation to get an average that includes the error factor of the rifle, ammo and shooter skill. If the 2nd bullet went 5.4" high how would your Exbal shootingsolution look then?

Jeff

 

[Broz]

Oops, looks like Scott andI were typing at the same time.

 

[Trickymissfit]

My first thout was the the data inputed into the equation was in error. But also you have to remember that the B/C often is close but never perfect from the manufacturer. Also I'd be running the rounds thru a couple chronographs to compair readings (really need three). Plus the equation used to figure the trajectory is not perfect. It has only been worked very recently by a kid in Germany, and you only came out .67 MOA off. So if you velocity was off 50fps and the manufacturer was off .05 on the B/C you have bad data going in. Also were you shooting on level ground? Even shooting slightly uphill at 800 yards will cause the point of impact to come in low. If it were me I'd add another three clicks in elevation and start over.
gary

 

[barnesuser28]

My first thout was the the data inputed into the equation was in error. But also you have to remember that the B/C often is close but never perfect from the manufacturer. Also I'd be running the rounds thru a couple chronographs to compair readings (really need three). Plus the equation used to figure the trajectory is not perfect. It has only been worked very recently by a kid in Germany, and you only came out .67 MOA off. So if you velocity was off 50fps and the manufacturer was off .05 on the B/C you have bad data going in. Also were you shooting on level ground? Even shooting slightly uphill at 800 yards will cause the point of impact to come in low. If it were me I'd add another three clicks in elevation and start over.
gary

actually if you are shooting uphill your impact will be higher than if on flat ground

 

[Trickymissfit]

actually if you are shooting uphill your impact will be higher than if on flat ground

the otherway around. it will be lower by a slight amount
gary

 

[Broz]

the otherway around. it will be lower by a slight amount
gary

Up or down hill shots lessen the amount of dial up needed. There for if the angle of the shot is not corrected for the shot will go high.

Jeff

 

[Browninglover1]

Up or down hill shots lessen the amount of dial up needed. There for if the angle of the shot is not corrected for the shot will go high.

Jeff

It's true, it took me a long time to grasp the concept, and I still don't understand all of the actual real world results (ex. riflemans rule gets you close, but not perfect) but trial and error has shown up or down hill angles will result in the need for less dial up.

 

[bigbuck]

I am not sure how accurate your gun is and how good of a shot you are and how confident you are in a 1 shot group but I would suggest at least shooting a group of 3 to find the center of your group. At 800 yards a 1/2 MOA gun will be shooting 4 inch groups. So your shot is only about an inch outside of that. Now if they all are shooting low then an adjustment needs to be made.

I can't run any numbers for you based off the info you gave so I am not going to be much help there. If you want comparison drops from another program you need to post muzzle velocity, bullet weight, BC, incline/decline. I agree with Roy most calculators don't like pressure and altitude both. It messes things up. I use station pressure only and eliminate altitude as the pressure accounts for it.

HTH,

Scot E.

My rifle has shot a 3 shot group at 752 yards that measured 2 1/2 inches . and it has shot a 333 yard 3 shot group that measured .631 . 200 yards looked like one hole that you could cover up with a dime. I will try and do a 3 ahot group the next time out thanks to all who has posted and tried to help me .

 

[bigbuck]

You might want to consider shooting a group instead of 1 shot. Then take the center of the group in eevation to get an average that includes the error factor of the rifle, ammo and shooter skill. If the 2nd bullet went 5.4" high how would your Exbal shootingsolution look then?

Jeff

okay thanks . I see .

roy I thought the more info I input into Exbal the better results i would get can you explain why the baro and elevation would work against each other ? thanks

 

[Scot E]

okay thanks . I see .

roy I thought the more info I input into Exbal the better results i would get can you explain why the baro and elevation would work against each other ? thanks

Pressure changes with elevation and with varying weather conditions but weather aside it will change as you increase or decrease altitude. So with some programs if you put in both readings they will give false readings if your settings aren't correct. I am not familiar with exbal so someone else will have to help you figure that out.

There are a couple ways to determine pressure too. Absolute, (sometimes called station pressure) will give you the correct pressure reading for the altitude you are at so you can leave the altitude field blank. At least that is how it works on most of the programs I use.

Scot E.

 

[royinidaho]

Gary/Riley one of you is correct regarding POI @ increasing angles....