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Vortex Strike Eagle BDC With Golden Tiger

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I'll post this here as a reference.

 

I'm putting a Vortex Strike Eagle 1-6X scope on my Sig556 Russian.  The Vortex AR BDC is set up for the 5.56 obviously so the hashmarks won't be right for the rainbow 7.62x39.  But if properly zeroed the AR BDC can be used out to 500yds very easily.

 

I did the calculations using Vortex ballistic calculator.  The ammunition I chose for my calculations is Golden Tiger.  Based on a BC of .300 and a velocity of 2375 and using a 50/150yd zero, here is what I get.

 

First column is yards, second column is the actual bullet drop, third column is the moa of the BDC hashmarks, fourth column is the difference.

 

100 . +0.9 .-0.0 . +0.9

200 . -1.5 . -2.4 . -0.9

300 . -5.6 . -5.6 . -0.0

400 .-10.9 .-9.5 . -1.4

500 .-17.5 -14.6 .-3.1

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All bullets begin dropping the second they leave the muzzle. Gravity: It's not just a good idea. It's the law.

Because of this we generally fire bullets slightly upward so that the bullet will rise to the sight plane, and often above it.
 

A very simple diagram which should help sort it out.

 

post-4831-0-84248500-1456767304.jpg

 

A complete explanation of external ballistics is a separate discussion but simply search "external ballistics" in Google for more details.

.

Edited by Darth Saigus
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It is surprising how many shooters, hunters and even reloaders have little understand of ballistics.

 

I know avid hunters that know nothing but a hard zero at some specific range.

To them every thing else is just "guess work"

Many folks never shoot over a hundred yards or so, never have much inclination or declination .

 

Unless new shooters study or are mentored by experienced and educated shooters ....they dont get the exposure.

For that matter, lots of older folks that have a lifetime of shooting have never really looked at it.

 

I hope Darths thread sparks some interest here

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I didn't think 7.62x39 had any drop at 200. I thought it was around 250 that it started. I knew at 300 and beyond it drops like a turd in a well.  

Every round drops the instant it leaves the muzzle.  You might have super-elevation for a zero at 100 or 200, but the round has arched upwards and then down to do that.

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I'll post this here as a reference.

 

I'm putting a Vortex Strike Eagle 1-6X scope on my Sig556 Russian.  The Vortex AR BDC is set up for the 5.56 obviously so the hashmarks won't be right for the rainbow 7.62x39.  But if properly zeroed the AR BDC can be used out to 500yds very easily.

 

I did the calculations using Vortex ballistic calculator.  The ammunition I chose for my calculations is Golden Tiger.  Based on a BC of .300 and a velocity of 2375 and using a 50/150yd zero, here is what I get.

 

First column is yards, second column is the actual bullet drop, third column is the moa of the BDC hashmarks, fourth column is the difference.

 

100 . +0.9 .-0.0 . +0.9

200 . -1.5 . -2.4 . -0.9

300 . -5.6 . -5.6 . -0.0

400 .-10.9 .-9.5 . -1.4

500 .-17.5 -14.6 .-3.1

 

So for quick and dirty field calculations, aim an inch higher than the hash mark per hundred yards after 300. That's easy enough.

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I was able to test this to 300yds and found it worked very well for 100, 200, and 300.

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I was looking at these numbers again for a range trip today and I realized that I was a bit unclear about the bullet drop numbers.  The bullet drop is in MOA, not inches.  So MOA times range in hundreds of yards gives the actual difference in inches.  Here is a more complete table.

 

I'll post this here as a reference.

 

I'm putting a Vortex Strike Eagle 1-6X scope on my Sig556 Russian.  The Vortex AR BDC is set up for the 5.56 obviously so the hashmarks won't be right for the rainbow 7.62x39.  But if properly zeroed the AR BDC can be used out to 500yds very easily.

 

I did the calculations using Vortex ballistic calculator.  The ammunition I chose for my calculations is Golden Tiger.  Based on a BC of .300 and a velocity of 2375 and using a 50/150yd zero, here is what I get.

 

First column is yards,

.........second column is the actual bullet drop in MOA, 

...................third column is the moa of the BDC hashmarks,

.............................fourth column is the difference in MOA,

......................................fifth column is difference in inches.

 

100 . +0.9 .-0.0 . +0.9  +0.9"

200 . -1.5 . -2.4 . -0.9   -1.8"

300 . -5.6 . -5.6 . -0.0   -0.0"

400 .-10.9 .-9.5 . -1.4   -5.6"

500 .-17.5 -14.6 .-3.1   -9.3"

 

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I didn't think 7.62x39 had any drop at 200. I thought it was around 250 that it started. I knew at 300 and beyond it drops like a turd in a well.  

 

At 200 the drop is -7.1998"

Velocity 1699 fps

Energy 788 lbs-ft

Edited by InTTruder

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It is surprising how many shooters, hunters and even reloaders have little understand of ballistics.

I hope Darths thread sparks some interest here

 

I guess I was fortunate growing up and learning to shoot rifles on the range at the club my Dad helped build. The rifle range had target stands at 50, 100, 150 and 200 yards. It was fun and a good learning experience starting out at the 50, then working our way out to the 200 and noticing how range and wind affected the results on-target.  :)

Someday I hope to get time in on a real long-range course and learn about much longer range shooting.

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I only use scopes with the mechanical BDC ballistic compisation option. All my rifles have its used for distance. I never go hunting without it. It’s harder to find them lately. BSA make one for the 223 round I haven’t tested it yet. I have the older top of the line bushnell with the bdc option and I tested them for years seal wise going from a woodstove heated camp to ten degree weather outside and never had a problem. I been chasing a 300lb buck that teases other hunters by staying out of range. Just give me one bullet for my 338wm.

I made a 170yd shot at a quarter sized target once using the bdc. She’s spot on.

 

Using a ballistics caculator you can get a idea about bullet drop and distance. On the certain 100 to 125yd calibers you can caculate where your best zero is for accuracy. Example the 7mm Mauser using a 125 yd zero the bullets path varies from the muzzle to 125 yds about 5/8” to 3/4”. Just a example.

Edited by Unknown Poster

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