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That can't be right!

Old 05-03-2023, 06:28 PM
  #11  
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Revisiting this one today - I recently had a conversation about the difference between MOA and MRAD with another shooter and it reminded me of this thread - when we look at trajectory compensation in inches, or even IPHY or MOA, the numbers get pretty big pretty fast, and the pattern can be a bit more difficult to remember... And that reminded me a bit of the "that can't be right"

For example - for my 6 Dasher, I can count on my fingers as a guide for my rough trajectory for every 100yrds, close enough to be within 2 clicks, from 300 out to 1200: I just recall that 300 is 1mil, then I start counting 400yrds at my left thumb at 1.5, then add a mil and 100yrds for every finger until I get to my right thumb, which is 900yrds, where I have to add an extra half mil, then 1mil to 1000, 1.5 for 2 fingers, and 2 for my last finger, gets me all the way to 1300yrds.

300 = 1.0
400 = 1.5 left Thumb (add 1 mil per 100yrds)
500 = 2.5 left index
600 = 3.5 left middle
700 = 4.5 left ring
800 = 5.5 left pinky
900 = 7.0 right thumb (added an extra half)
1000 = 8.0 right index (just 1mil here)
1100 = 9.5 right middle (1.5 per 100 now)
1200 = 11.0 right ring
1300 = 13.0 right pinky (2mils)

I won't be wrong by more than 2-3 clicks on any of these distances:

Estimated vs. Actual
400 = 1.5 ~ 1.7
500 = 2.5 ~ 2.6
600 = 3.5 = 3.5
700 = 4.5 = 4.5
800 = 5.5 ~ 5.6
900 = 7.0 ~ 6.8
1000 = 8.0 ~ 8.2
1100 = 9.5 ~ 9.6
1200 = 11.0 ~ 11.3
1300 = 13.0 ~ 13.1

But what's maybe more relevant for this particular thread - 13mils seems like a relatively small and manageable number, and 11 vs. 13 doesn't seem to be terribly extreme It seems a little more surprising when we consider this compensation difference in MOA - as that 2mil gap becomes ~7moa. However, if we think about that difference in linear offset instead of subtensions, that difference is actually 10 1/2 feet of difference between 1200 and 1300 yards, and the total drop compensation at 1300yrds is 51ft 2in... It's a heck of a lot easier to remember 13mils at 1300yrds than 614 inches!

Last edited by Nomercy448; 05-03-2023 at 07:40 PM.
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Old 04-14-2024, 05:24 PM
  #12  
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Revisiting this thread AGAIN - I shot a Pro Series PRS match last weekend here in Kansas, during which we saw gusts up over 40mph, some gusts up over 50. My highest wind hold for the day was 6.1 mils at 1040yrds, shooting in a prevailing 28mph wind at my 2:30 - which is 19 feet of WIND drift. Every 2mph wind bracket was halfway across the plate, and most of our 30sec wind captures were seeing 10-12mph variability in wind speed. It was brutal.
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Old 04-22-2024, 11:47 AM
  #13  
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I shot this weekend with my new "big gun," and was explaining to another shooter behind the line the actual significance of what we were doing - looking through the spotting scope, we tend to lose perspective on just far apart are our line of sight and our bullet trajectory when we are shooting long, long distances.

I had an opportunity to shoot 2913yrds this weekend, and for my first round impact on the target, I sent 35.5 mils of correction (I dialed 30.5mils on my scope, since my capacity was only 32.5), then held 5 mils in the reticle. Thinking of 5 mils in the optic, that really didn't feel like too much - not so different than when I HOLD OVER from my 100yrd zero when shooting at ~750yrds, since both would be a 5mil hold in the reticle... but recalling the 30.5mils extra dialed, PLUS the 5 mils held, totaling 35.5, I had to acknowledge that I was actually aiming my bore more than100yrds (310ft 3in, to be exact), higher than the 48" target (1.6moa at 2913yrds).

Not very often in my life have I had opportunity to need to hold 100yrds ABOVE target to guide bullets where I wanted them to go. It's a really intense experience.
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Old 04-23-2024, 02:00 PM
  #14  
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what. chambering?
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Old 04-24-2024, 01:33 PM
  #15  
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It's a 375 Cheytac, I'm sending 400grn Cutting Edge Lazers out at 3050fps. I live an hour from one of the most pre-eminent ELR competition ranges in the country, so I don't have much excuse for not having a rifle to go play.
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Old 04-24-2024, 02:08 PM
  #16  
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Originally Posted by Nomercy448
It's a 375 Cheytac, I'm sending 400grn Cutting Edge Lazers out at 3050fps. I live an hour from one of the most pre-eminent ELR competition ranges in the country, so I don't have much excuse for not having a rifle to go play.
good answer!
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