chairgun pro isnt accurate????

[Guest]

Hey guys. First time out at my range today with my new .25 wildcat, zeroed the scope at 50 yds, but all the hold over and hold under numbers weren't matching chairgun pro or strelok. As far as I know I put in all the correct numbers. Jsb 25.4 domed - 900fps- bc .018- scope height 2.8 inches- scope zero 50yds- moa 1/4in. at 100yds. Hawke 20x half mildot . - Magnification 20x. Am I missing anything?

 

[MattChastain]

some times the bc is not perfect for the setup you are using. Normally to get a perfect match i calculate my own bc by plugging in data into chairguns bc calculator. there is also a chance that your chronograph is not showing correct velocities. 

 

[Dave]

Chairgun gives Ballistic coefficient of .0360 that would mess up your holdover and hold under.

 

[Froggy.]

BC =.0360

 

[FearnLoading]

"FastEddie"Hey guys. First time out at my range today with my new .25 wildcat, zeroed the scope at 50 yds, but all the hold over and hold under numbers weren't matching chairgun pro or strelok. As far as I know I put in all the correct numbers. Jsb 25.4 domed - 900fps- bc .018- scope height 2.8 inches- scope zero 50yds- moa 1/4in. at 100yds. Hawke 20x half mildot . - Magnification 20x. Am I missing anything?

Yep. Ballistic coefficient is 0.036 for the JSB 25.4 grains.
You will also need to enter in Sterlok the magnification at which your scope is TRUE. This could be at 10x or 20x for you. Hawke makes both models. I think yours will probably be 10x. Find that out.

In Sterlok, You need to put the ranging magnification at the value at which the scope is true which could be 10x or 20x for you. Once you have the BC and the ranging magnification fixed, it will work flawlessly. 

 

[Adam]

scope height is another to make sure is accurate

 

[azuaro]

"scope height is another to make sure is accurate"
Absolutely!...This is probably the one variable that makes those ballistic tables inaccurate for some people...

To get a very precise measurement, use calipers and measure from the top of the scope at the edge of the objective to the bottom of the barrel, then measure the scope objective and barrel diameters and subtract 1/2 of each to the first measurement and that is your center of barrel to center of scope measurement (Scope Height)...

Regards,

AZ

 

[Guest]

Thanks guys. Ill give that a try.

 

[Guest]

I put in the correct data, thanks to you all, and the numbers matched to the notes I took in the field. Thanks again guys