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 Questions concerning extreme distance shooting

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Randy

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PostSubject: Questions concerning extreme distance shooting   Tue Nov 08, 2011 4:44 pm

Not really a range report, I just felt this topic belonged here.

We had a discussion on the drop of a bullet at extreme distances on another forum and I was wondering what the drop is and how it's measured (from what point in it's flight)?
After reading my book on accuracy and bench rest shooting this still isn't clear to me.

The question was- what's the MOA of a bullet at 2000 meters? The proposed answer is 225 FEET.

I am not arguing this assumption/fact, but would like to know if it is in reality a fact or theory?

In order to assume that it drops 225 feet then it stands to reason that the gun would be pointing to that elevation above the target on flat land. If gravity causes the bullet to form a perfect arc as it ascends and then descends, then the bullet theoretically hits the apogee at 1000 meters which would be the point of aim (of the muzzle of the gun) correct? But this can't happen outside of a perfect vacuum, so in reality the bullet can't fly in a perfect arc and would be acted upon negatively by drag in the atmosphere which would cause the bullet to slow exponentially as it moves father from the muzzle thereby creating more of an ellipse than a true arc since as the bullet slows it's descent will accelerate also. (Note- insert the correct terminology where appropriate) I realize the flight time of a bullet at that close of a distance is measured in a very few seconds (2? 3? at most) however this still seems to be enough time to be acted upon by the density of the atmosphere since it can be acted upon severely by a cross wind at much shorter distances.
So can anyone clear this up on a level that I can understand it? Lots of mathematics would only serve to confuse me more. Are there any websites that clearly explain this? I've sorta looked but haven't found a good one yet. Thanks!
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PostSubject: Re: Questions concerning extreme distance shooting   Fri Nov 11, 2011 5:01 am

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Great question. I seen your convo about this earlier, and actually used the 225ft number to impress upon a young cat about trajectory and bullet drop etc. Cause he asked the obligitory Rolling Eyes question 'how far can it shoot'.
I would think there is a ballistic calc out there that would figure it out. Infact, I know I have played with one before. I will look.
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PostSubject: Re: Questions concerning extreme distance shooting   Fri Nov 11, 2011 5:08 am

448in drop at 1000yds [You must be registered and logged in to see this image.]
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Randy

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PostSubject: Re: Questions concerning extreme distance shooting   Sat Nov 12, 2011 2:27 am

Shocked Yeah, I was hoping you'd recognize your answer over there Wink, So now the answer is 448 INCHES or 4.48 Inches? Suspect I haven't looked yet. 448"=37.33' I never did get out to see where mine aims when I aim a mile out. Prolly won't work anyway because I live on top of a hill.

BTW- what would you consider to be the maximum distance a 7.62 bullet could actually stay in the air if shot at a target a mile and a quarter away? It should hit the ground if shot within the sight allowance on the rear sight I would think. [You must be registered and logged in to see this image.] Think I'll go look at that chart now. [You must be registered and logged in to see this image.]
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PostSubject: Re: Questions concerning extreme distance shooting   Sat Nov 12, 2011 3:14 am

Randy wrote:


BTW- what would you consider to be the maximum distance a 7.62 bullet could actually stay in the air if shot at a target a mile and a quarter away?

I think we need a trig expert here. lol I have a friend that is good at that. I hate it when he explains it cause its pretty simple half the time. I have to hit myself for not thinkin it through. But I kid myself. Im not gonna. lol

If the bullet could reach 1.25mi, it damn sure would be comin in at a STEEP angle. Thats all I know. lol

Hmmm, i think we should keep kicking this dead horse. I bet it will release the answer eventually. Let me look around.
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PostSubject: Re: Questions concerning extreme distance shooting   Sat Nov 12, 2011 9:58 pm

Well, the .22 bullet is supposed to travel a mile (say's so right on the box) so I just assumed the 7.62 would travel twice that distance. [You must be registered and logged in to see this image.]
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PostSubject: Re: Questions concerning extreme distance shooting   Sun Nov 13, 2011 2:48 am

[You must be registered and logged in to see this link.] Heres a ballistic calculator. I will try to mess with it.
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PostSubject: Re: Questions concerning extreme distance shooting   Mon Nov 14, 2011 1:57 pm

says 111ft. The aiming angle is 167.6moa lol

.308 180gr .507bc 2000yds 2600fps
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PostSubject: Re: Questions concerning extreme distance shooting   Tue Nov 15, 2011 3:07 am

Sorry for the delay, I've been busy outside getting electricity to an old shed and I started school again today.

Anyway, I guess that about proves it then. A question still remains in my mind however, regarding the actual drop after the 1200' mark. Does the bullet maintain a smooth arc during descent or does it make a faster arc as more distance passes and the bullet slows even more? In other words will the bullet pass the line of site line AT or very near the 2400' mark or will it fall much shorter? Inquiring minds want to know. Very Happy
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PostSubject: Re: Questions concerning extreme distance shooting   Tue Nov 15, 2011 3:19 am

I think the answer might be on page 2 here [You must be registered and logged in to see this link.]
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PostSubject: Re: Questions concerning extreme distance shooting   Tue Nov 15, 2011 3:23 am

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PostSubject: Re: Questions concerning extreme distance shooting   Tue Nov 15, 2011 3:26 am

Shocked Figure 1 was about all I could comprehend from that but it told the story at least for the size projectile they where discussing.
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PostSubject: Re: Questions concerning extreme distance shooting   Sun Mar 17, 2013 4:27 pm

Ok. I did some tinkering and searching. Basically found a nifty tool at Ammoguide.com (ballistic calculator)

A Nosler .308 (.505bc) pushed to 3200fps muz velocity. Trajectory to 2000yds

To obtain a 2000yrd zero, the departure angle is 113.8moa. Peak bullet height is 78.8ft above zero.

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PostSubject: Re: Questions concerning extreme distance shooting   Fri Jun 05, 2015 12:44 pm

I know this is an old thread but jonesin for some mosin talk I've been looking threw old threads

now I'm no expert in this but I have read a lot and researched this a bit
in Silvertips chart above it proves that a 7.62x54r bullet will in fact travel out to 2000 yards
but will it be accurate.? and from what I understand the answer is no

some bullet designs are better than others and I'm not sure how to find this out
but the problem is a bullet flying faster than the speed of sound is flying supersonic
the speed of sound changes with changes in barometric pressure but for argument's sake
the lets assume the speed of sound is 1200fps once the bullet flies faster then the speed of sound
it breaks threw its own pressure wave and the spin and shape keep it stable
as it slows threw the transonic zone 1200fps the bullet becomes unstable and can even start tumbling
because the pressure wave changes how it acts upon the bullet basically the bullet kind of jackknifes
the rear try's to overtake the nose no matter the spin (some bullets handle this better than others)
so most people consider a bullet is only accurate out to the point that it slows past the speed of sound
the bullet will fly a lot farther than it is accurate
in the chart above I wouldn't try to hit anything past 1200 yards
so the faster the bullet starts out and the better the ballistic coefficient
the longer it can retain its speed and that gets you accurate distance
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PostSubject: Re: Questions concerning extreme distance shooting   Fri Jun 05, 2015 5:16 pm

You are asbolutely correct. shweet

Thats how I calculate it anymore. 1200fps min.
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PostSubject: Re: Questions concerning extreme distance shooting   Sun Jun 07, 2015 11:18 am

this is cool I found this on JBM Ballistics its a max distance calculator
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so I put in my current load #32 which is 174g Sierra Match King .311 HPBT with a BC of .499
put in my MV temp barometric pressure humidity and altitude
and presto

so if I'm reading this right
if I shoot up at a 32.5 degree angle my bullet will go 5156.7 yards


Maximum Distance
Input Data
Manufacturer:SierraDescription:HPBT MatchKing™
Caliber:0.311 inWeight:174.0 gr
Muzzle Velocity:2594.0 ft/s
Temperature:70.0 °FPressure:29.84 in Hg
Humidity:15.0 %Altitude:2100.0 ft
Std. Atmosphere at Altitude:NoPressure is Corrected:No
Output Data
Atmospheric Density:0.07459 lb/ft³Speed of Sound:1128.2 ft/s
Initial Angle:32.5 degTerminal Angle:61.1 deg
Terminal Range:5156.7 ydTerminal Velocity:471.1 ft/s
Terminal Time:30.8 sTerminal Energy:85.7 ft•lbs
07/06/15 08:01, [You must be registered and logged in to see this link.]/[You must be registered and logged in to see this link.]
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PostSubject: Re: Questions concerning extreme distance shooting   Sun Jun 07, 2015 11:20 am

:sceered:
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