develop a drop chart by shooting at several distances out to the limit of your rifle.
Record the velocity of each shot.
Measure the drop at each distance or count clicks and measure if adjusting for each distance.
Feed this data into something like JBM after entering the proper and accurate set up data.
Four items will be critical.
- line of sight above line of bore.
- Accurate muzzle velocity.
- Accurate drop measurements.
- Accurate atmospheric conditions
If the initial drop data doesn't fit then, adjust MV to see if it can be made to fit. If not the go back to the original measured velocity and change bc to make it fit.
If it doesn't fit with this, adjust MV and bc to make it fit.
If it still can't be made to fit redetermine the line of sight about line of bore.
There ain't no free lunch.
Once you get it to fit your MV may not be as measured and your BC may not be as published but you will hit what your shootin' at more times than not.
I've been told that different barrels cause a difference in BC which is a consideration also.
Also I find it difficult to notice any difference in the third decimal point value. Thus my BCs are logged as 0.XX instead of 0.XXX.