A couple of ways to check. At 100yds, put up a tape measure on a board. Zero the rifle at the bottom (shoot a rd). Dial up the scope and shoot at the different come ups. See where the bullets actually land.
If the scope is off, you will quickly see. Example, you dial up 10 min but your actual bullet impacts 12 min high. The scope moves more then expected so it looks like your bullet is flying flatter then it actually does.
If all the come ups check out, shoot at your favorite distances but on a MOA sized target. Shooting and hitting a 40" rock does allow for some degree of error (2MOA or more). If you shoot and hit a 11" target at 1100yds, well then you would have to say things are dialed in.
Finally, what drag function are you using in your data. That is the G number usually required. Most programs default to G1 which is usually wrong for boattail bullets.
If everything else checks out, change the G function but keep all other data the same. It might bring your data in line with real world observations.
That is what I had to do with recent shooting of the 162gr Amax from 2 7RM. By changing the G function, I was able to get my data and real world come ups to agree.
Hope this helps. Try and get yourself a chronie. Would reduce the amount of guesswork.
If you have access to a ballistic computer you can usually reverse engineer your data. However, you need good input data. The BC that Sierra advertises is a baseline, your gun with your load and velocity may change it a bit.
When I see folks doing this, the biggest mistake in reverse engineering is the scope height. Most use a standard 1.5 inches that comes in the ballistic computers. You need to measure it and use the correct height.
Then once you have all the input data, start playing with the BC until it closely matches your actual data. You won't get it exact, but you should be able to get close.
Hope it helps,
Distance is not an issue, but the wind will make it interesting!
I just thought I would update all that have replied to this post. First off, thank you for enlightening me to my dilema. Second, I have no idea what I was thinking. I posted this question w/o even giving a second thought as to what I should do.
I scratched my head and decided that something was WAAAAY wrong and loaded up the rifle and gear and went to the range. Well to make a long story short, My firt shot was 6" high at 100 yds. Need I go on?? I didn't think so. Re-zeroed the scope and wouldn't you know, my ballistic drop tables were right all the time.
Thank you all.
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