Post by bluedot on Jan 13, 2021 23:43:38 GMT -5
Awesome, you started this thread with:
What went wrong is that you plugged the wrong numbers into the ballistics calculator.
PERIOD.
END OF DISCUSSION.
I didn't do anything with a calculator until the day I posted this thread.
You guys are nuts. You're very helpful, but very unhelpful at the same time. Nobody has even tried to answer the very specific question I've been asking. Everyone's fixated on my scope and bore height.
I appreciate the replies. I'll come back to this thread once I get a dope chart figured out. 4-H stuff keeping us busy all week, so it won't be until this weekend at the earliest.
The answer to "I understand that the subsonics will drop off more as distance increases, but... at 20 yards I should still be pretty much dead on, right?" (your question) is maybe. What you aren't understanding is that sight height makes a HUGE difference in where the bullet impacts, especially at closer distances. If you had the correct data in the ballistic chart than an answer could be given, but without that data it is impossible to guess. The thing that you cannot see in the data that you posted is where the subsonic bullet impacts with the sights set on the zero for the supersonic round.
You also asked "I guess my real question is how do I plug the numbers in so I can compare POI between two loads? Do I have to re-zero my scope for both loads in order to compare them accurately? I was trying to avoid that so I could get hold-over numbers. I don't know if I'm making this clear enough. I just want to know my POI shift from load-to-load at 20-100 yards. I now realize the numbers I put into the calculator aren't going to be accurate because of the way it works."
The answer is you can't plug the numbers in unless you know the sight height and the actual zero for the rifle with the bullet/load that you are shooting. BUT, I will hop on the calculator and try to give you an example. These numbers are from a 5 yd zero, the lowest my program will calculate. The following numbers are POI using that 5 yd zero, NOT a 100 yd zero.
Subsonic Supersonic
Sight Height +.5 +2.5 +.5 +2.5
0yd -0.5 -2.5 -0.5 -2.5
20 1.02 7.02 1.29 7.25
40 1.27 15.27 2.53 16.53
60 0.21 22.21 3.18 25.18
80 -2.16 27.84 3.25 38.25
100 -5.87 32.13 2.68 40.68
120 -10.94 35.06 1.48 47.46
140 -17.42 36.58 -0.36 53.64
160 -25.26 36.44 -2.87 59.13
180 -34.99 35.01 -6.08 63.92
200 -45.73 32.27 -10.02 67.98
With a 100 yd zero on the supersonic round, with a sight height of +2.5" I have no idea where the subsonic round will impact. To get a 100 yd zero with the supersonic round you have to adjust the scope up 40.68" at 100 yes from the 5 yd zero shown above. What does that do to the POI for the subsonic round shot with that scope setting? I have no idea. This is exactly why we are asking for the sight height, we aren't asking to get more typing practice. You cannot correlate the 2 loads due to the sight height. You will just have to shoot them and see - again taking into consideration the center of group that you shoot at that distance - you CANNOT go off of a 1 shot group for that information.
You CANNOT use the above data for the difference in POI at 20 yds because the above data used a zero of 5 yds, not 100 yds.
Using the 100 yd zero for the supersonic round, and a 2.5" sight height, it should impact -0.84" at 20 yds. How that correlates to the subsonic POI at 20 yds I have no clue.
Let me update this with info from your last post. You said in your last post " The ONLY thing I care about is how much MORE drop I get from one load over a different load. The gun itself is irrelevant, beyond the length of the barrel. You are all missing this point. I don't care about any of the other data AT THIS POINT."
As you can see from that 4 charts above, without knowing the sight height and what distance the gun is sighted in at for that particular round there is no way to answer your question. You cannot calculate the correlated bullet drop from knowing a 100yd zero with the supersonic load to the other load when there is that much discrepancy in the point of impact due to the scope height and the amount of bullet drop between the 2 loads. As you can see it isn't linear.
The ONLY way you will get the data that you are wanting to calculate is go and shoot 3-5 shot groups at the different yardages. Better bring a tall piece of cardboard because I'm thinking you will see a very large difference in bullet POI.