Trajectory Calculation

[HOGGHEAD]

I need help with a little math problem. I have not figured out a math problem like this since college. And that was well over 30 years ago. So I need a little help.

I want to calculate how high my bullet is hitting at 100 and 200 yards with the following data.

1. Bullet is a 75 grain A-Max with a BC of .435 in a 22-250.

2. When I did my load data the only distance I shot was 300 yards. I prefer to check my loads at longer distances than 100 yards. 300 yards is a great distance. You can really sort out the loads as long as you can call the fliers.

3. The rifle is sighted dead on at 300 yards. And shooting unbelievable groups at that distance.

4. Scope is a 6.5X20 Zeiss Conquest with TT's. The scope adjustment is 1/4 MOA per cick.

5. I also shot the rifle at 400, 500, and 600 yards. But not enough at 600 yet to get a perfect zero.

6. At 400 yards I need to raise the scope 9 clicks to change the zero from 300 to 400 yards.

7. At 500 yards I need to add 7 more clicks to the 400 yard zero to hit dead on at 500 yards.

8. So I have a total of 16 clicks to raise the zero from 300 to 500.

9. I want to leave the scope zeroed at 300 yards then dial in my 400 and 500 yard shots.

According to my reloading data my load should be about 3200 fps. But I did not chrono the load. So I do not know that for sure. The barrel on my rifle is 28", so the loads could be a little different.

What I would like to calculate is when my rifle is zeroed at 300 yards. What will be my point of impact be at 100 and 200 yards.

Now I realize it would be easier to go to the range and just shot the rifle at 100 and 200 yards. But that is not an option right now. I want to take the rifle hunting and since I am handicapped I can only get out once or twice a week. So my options are to go hunting a day or two or take a day off ground hog hunting and take another day to the range. I would prefer to hunt, but I would really like to know where my bullet is impacting at 100 and 200 yards.

Do I have enough information to calculate that?? And if so then what would that trajectory be?? I did try to enter some numbers into a ballistic calculator, but I did not do so well. Thanks, Tom.

 

[MALLARD]

Re: Trajectory Calculation

did you look at the g7 ?

 

[HOGGHEAD]

Re: Trajectory Calculation

g7?? No idea what that means. Tom.

 

[427Cobra]

Re: Trajectory Calculation

JBM Ballistics

 

[HOGGHEAD]

Re: Trajectory Calculation

Yes I cheked a ballistics calculator. But I am questioning my findings. That is why I asked this question. I was hoping someone would know how to determine the height, and the actual velocity. Wish my chrono was not broken. I need to buy a new one(shortly!!). Tom.

 

[Suasponte]

Re: Trajectory Calculation

 

[427Cobra]

Re: Trajectory Calculation

People who count clicks are suckers, you might be mentally handicap if you continue that practice, you spent your good hard earned money on a good scope, trust the turrets, zero them out, now simply dail whatever your come up is for the distance your shooting, I would recommend a 100 yard zero, that will make your come ups very easy to repeat, having a 300 yard zero makes life complicated, now you have to worry about come ups and come downs, I agree with doing load development at 300, but I do it with a 100 yard zero.

 

[supratt96]

Re: Trajectory Calculation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: HOGGHEAD</div><div class="ubbcode-body">Yes I cheked a ballistics calculator. But I am questioning my findigs. That is why I asked this question. I was hoping someone would know how to determine the heighth, and the actual velocity. Wish my chrono was not broken. I need to buy a new one(shortly!!). Tom.
</div></div>

My home range only goes out to 100 yds, so that is where I typically have my rifles zero'd. But, I occassionally shoot mid-range f-class at 600 yds. With two different rifles/calibers, I have found the ballistic calculators to be dead on. I dial in the indicated elevation and my first shot is within a few inches every time.

If you put the correct information in, you can trust the results.

 

[HOGGHEAD]

Re: Trajectory Calculation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 427Cobra</div><div class="ubbcode-body">People who count clicks are suckers, you might be mentally handicap if you continue that practice,
</div></div>


Thanks alot. I was hoping I might get in a discussion with someone who really knew MOA and could help me out here a little bit. But instead I get a knot head reply like yours. Thanks alot for the help. Or should that be thanks for nothing?? Tom.

 

[Tripwire]

Re: Trajectory Calculation

He's pretty much right about counting clicks, a huge waste of time compared to other methods....

JBM is your friend for calculating dope, but NOTHING replaces rounds down range to confirm the calcs.

I zero at 200 for most of the shooting I do with precision bolt rifles...the difference between 100 and 200 is not enough for me to fret over, and I simply do not worry about range or comeups until I'm out past the 200 yard zero.

 

[427Cobra]

Re: Trajectory Calculation

Listen if we weren't a 1000 miles apart I would gladly help you face to face, everybody needs shooting buddies, I'm sorry if I offended you, but I was serious about counting clicks, and 100 yard zero, I'm also guessing you don't have a MOA reticle, if you did you could use the reticle to hold low with great accuracy, the difference between 100 and 200 is about .75 inch, hold about 3.5 inches low and wack any animal at those distances. Next time you go to the range just dial your come ups, don't count, log in your log book if you have one your come ups/downs and where your hits are, if you don't have a logbook I will give one from a prize table I picked up.

 

[HOGGHEAD]

Re: Trajectory Calculation

I was not offended. I have thick skin. I am just not sure how calling another member "Mentally handicapped" and a "sucker" can be construed as constructive help?? Or even criticism?? If you care to call it criticism.

"Counting clicks" was just a term I used to describe what I was doing. And I did not want to describe it as exact MOA differences because I did not calculate that exact figure. Maybe I should have, my mistake.

I rarely shoot this rifle at ground hogs under 300 yards. That is why I sight it in at 300, then dial up from there.

I was realy wondering about a velocity that I attained.

I have tried to calcualte it several times using a ballistics calculator and I keep coming up with 3400 fps. Which I thought was a little high for a standard 22-250. But I have recently had a few conversations with some guys who also attained 3400 to even 3450 with the standard 22-250 in the longer tubes.

And my question about height at 100 and 200 yards was just a reference for me in the future. And in case I do decide to take an occasional shot at a shorter range ground hog. And we all know it is goiong to be roughly in the 3" high range at 100 yards. That is common sense from shooting rifles for over 40 years.

Probably not the way a competitor zeroes a rifle for competition. But my shooting is from 300 to 600 yards for ground hogs with this rifle. And out to 800 when I get a little more range work. That is why I started my zero trajectory at 300 yards. Tom.

 

[BobinNC]

Re: Trajectory Calculation

Tom,

Here's your chart:

0 *** *** *** ***
100 10.9 2.7 2.4 0.6
200 7.0 1.7 4.9 1.2
Note: Hold overs, below 300 yds
300 -0.0 -0.0 7.7 1.9
400 -8.5 -2.1 10.7 2.7
500 -18.4 -4.6 14.0 3.5
600 -29.7 -7.4 17.5 4.4
700 -42.7 -10.7 21.4 5.4
Note: Hold unders above 300 yds

First column is yds
Second is 1/4 MOA clicks
Third is drop in MOA
Fourth is windage 1/4 MOA clicks in a full value 10 mph wind
Fifth is windage in MOA in a full value 10 mph wind

Comments:

I used the G7 factor for the 75 grain A-Max @ 3250 FPS. The clicks are shown in tenths, but you can only dial whole clicks, so round up.

Your drops, as 9 clicks to get to 400 yds, and 7 more to get to 500, are incorrect. Not that you did not record that, but it is contrary to the laws of physics. So your 500 yd target was either not a full 500 yds away or you had a tail wind that affect your drop.

What I mean is, your drop from 400 to 500 yds, should be the same as or greater than your drop from 300 to 400 yds, but it cannot be less. Unless there is a up or down angle not mentioned or wind may have been a factor. My calculation shows you would need 19 clicks from a 300 yd zero for 500 yds.

Next my understand is that Zeiss Conquests have 1/4" (0.25") adjustments, not 1/4 MOA (0.262"). Have you tested your adjustments to see what you actually have?

Bob

 

[HOGGHEAD]

Re: Trajectory Calculation

Thanks Bob. I would like to ask a question or two if I may??

The reason I said 1/4 MOA for the scope adjustment is because that is what my manual and the Zeiss web site says the adjustment is. I will triple check the knobs to see what they say. Thanks for that.

When I was dialing from 300 to 400 I dialed in (supposedly) 2-1`/4 MOA(trying to use a better term-not clicks) And my bullets hit high in the bullseye. Then I dialed an additional 1-3/4 MOA to zero at 500 yards. But I believe if I dialed back down 8 clicks or 2MOA instead of 7 clicks I would still be in the lower part of a 1" bullseye. So the actual calculation could also have been. 8 clicks up to 400, and 8 more up to 500 yards. Could that possibly sound more realistic??

However your velocity of 3250 sounds more realistic to me. I did not think I was actually getting 3400 fps with 36.0 grains of H-414 and the 75 A-Max. Even though I am shooting a 28" barrel.

Thank you for taking the time and looking into this for me. I do appreciate it.

I have not tested the Zeiss scope for exact measurement. I did do a box test. But I did it in reference to assure the scope was returning to zero, and did not get out a ruler and actually measure the movements. In retrospect I see now that was a mistake(not measuring). I won't make that mistake again.

Again thank you for taking to time to figure it backwards for me. I thought I was making a mistake when I came up with 3400 fps. I am going to order a new chrono very soon. However it is time to hunt with this rifle. I will get in some more range time with it after ground hog season, but now I only get a few trips. So that will be to hunt instead of going to the range. The "hogs" are calling me.

And Bob you are right. I could have made a mistake or two. I am not an expert. But I try as best I can. However the distance measurements are dead on. I was shooting at our local 1,000 range here in WV. And those older fellows are accurate on the tape measure. Thanks Again, Tom.