Rifle Scopes MK262/77 TMK Battle Zero

[nick338]

This is actually a 2 part question. Where do users of this ammo zero their carbines and not sure I understand the 50/200 or 36/300 zero. I'm just used to "zeroing" the rifle at 200 yards and only being 1" or so high at 10 yards and everything else good in between.

I'm hearing people "zeroing" at 50 and having the path of the bullet cross again at 0.0 at 200 yards and this isn't making sense to me. My numbers on JMB are showing 4.3" drop at 200 when "zeroing" at 50.

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[nick338]

50 YARD ZERO

Trajectory Input Data Ballistic Coefficient: 0.410 G1 Caliber: 0.224 in Bullet Weight: 77.0 gr Muzzle Velocity: 2600.0 ft/s Distance to Chronograph: 10.0 ft Sight Height: 1.50 in Sight Offset: 0.00 in Zero Height: 0.00 in Zero Offset: 0.00 in Windage: 0.000 MOA Elevation: 0.000 MOA Line Of Sight Angle: 0.0 deg Cant Angle: 0.0 deg Wind Speed: 7.0 mph Wind Angle: 90.0 deg Target Speed: 10.0 mph Target Angle: 90.0 deg Target Height: 12.0 in Temperature: 59.0 °F Pressure: 29.91 in Hg Humidity: 50 % Altitude: 800.0 ft Vital Zone Radius: 5.0 in Std. Atmosphere at Altitude: No Pressure is Corrected: Yes Zero at Max. Point Blank Range: No Target Relative Drops: Yes Mark Sound Barrier Crossing: No Include Extra Rows: No Column 1 Units: 1.00 in Column 2 Units: 1.00 mil Round Output to Whole Numbers: No Output Data Elevation: 4.119 MOA Windage: 0.000 MOA Atmospheric Density: 0.07402 lb/ft³ Speed of Sound: 1116.5 ft/s Maximum PBR: 313 yd Maximum PBR Zero: 266 yd Range of Maximum Height: 147 yd Energy at Maximum PBR: 674.7 ft•lbs Sectional Density: 0.219 lb/in² (yd) (in) (mil) (in) (mil) (ft/s) (none) (ft•lbs) (s) (in) (mil) Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead Calculated Table 0 -1.5 *** 0.0 *** 2607.1 2.335 1161.9 0.000 0.0 *** 5 -1.3 -7.2 0.0 0.0 2596.5 2.326 1152.4 0.006 1.0 5.6 10 -1.1 -3.0 0.0 0.0 2585.8 2.316 1143.0 0.012 2.0 5.6 15 -0.9 -1.7 0.0 0.0 2575.2 2.307 1133.7 0.017 3.1 5.7 20 -0.7 -1.0 0.0 0.0 2564.6 2.297 1124.4 0.023 4.1 5.7 25 -0.6 -0.6 0.0 0.0 2554.1 2.288 1115.1 0.029 5.1 5.7 30 -0.4 -0.4 0.1 0.0 2543.5 2.278 1106.0 0.035 6.2 5.7 35 -0.3 -0.2 0.1 0.1 2533.0 2.269 1096.8 0.041 7.2 5.7 40 -0.2 -0.1 0.1 0.1 2522.6 2.259 1087.8 0.047 8.2 5.7 45 -0.1 -0.1 0.1 0.1 2512.1 2.250 1078.8 0.053 9.3 5.7 50 0.0 0.0 0.1 0.1 2501.7 2.241 1069.8 0.059 10.3 5.7 55 0.1 0.0 0.2 0.1 2491.3 2.231 1060.9 0.065 11.4 5.8 60 0.1 0.1 0.2 0.1 2480.9 2.222 1052.1 0.071 12.5 5.8 65 0.2 0.1 0.3 0.1 2470.5 2.213 1043.4 0.077 13.5 5.8 70 0.2 0.1 0.3 0.1 2460.2 2.204 1034.6 0.083 14.6 5.8 75 0.2 0.1 0.3 0.1 2449.9 2.194 1026.0 0.089 15.7 5.8 80 0.2 0.1 0.4 0.1 2439.6 2.185 1017.4 0.095 16.7 5.8 85 0.2 0.1 0.4 0.1 2429.3 2.176 1008.9 0.101 17.8 5.8 90 0.2 0.1 0.5 0.2 2419.1 2.167 1000.4 0.108 18.9 5.8 95 0.2 0.0 0.5 0.2 2408.9 2.158 991.9 0.114 20.0 5.9 100 0.1 0.0 0.6 0.2 2398.7 2.148 983.6 0.120 21.1 5.9 105 0.0 0.0 0.7 0.2 2388.5 2.139 975.3 0.126 22.2 5.9 110 -0.0 -0.0 0.7 0.2 2378.4 2.130 967.0 0.133 23.3 5.9 115 -0.1 -0.0 0.8 0.2 2368.3 2.121 958.8 0.139 24.4 5.9 120 -0.3 -0.1 0.9 0.2 2358.2 2.112 950.6 0.145 25.6 5.9 125 -0.4 -0.1 1.0 0.2 2348.1 2.103 942.5 0.152 26.7 5.9 130 -0.5 -0.1 1.0 0.2 2338.1 2.094 934.5 0.158 27.8 5.9 135 -0.7 -0.1 1.1 0.2 2328.0 2.085 926.5 0.164 28.9 6.0 140 -0.9 -0.2 1.2 0.2 2318.0 2.076 918.5 0.171 30.1 6.0 145 -1.1 -0.2 1.3 0.2 2308.1 2.067 910.7 0.177 31.2 6.0 150 -1.3 -0.2 1.4 0.3 2298.1 2.058 902.8 0.184 32.4 6.0 155 -1.5 -0.3 1.5 0.3 2288.2 2.049 895.0 0.190 33.5 6.0 160 -1.8 -0.3 1.6 0.3 2278.3 2.041 887.3 0.197 34.7 6.0 165 -2.0 -0.3 1.7 0.3 2268.4 2.032 879.6 0.204 35.8 6.0 170 -2.3 -0.4 1.8 0.3 2258.5 2.023 872.0 0.210 37.0 6.0 175 -2.6 -0.4 1.9 0.3 2248.7 2.014 864.4 0.217 38.2 6.1 180 -2.9 -0.4 2.0 0.3 2238.9 2.005 856.9 0.224 39.3 6.1 185 -3.2 -0.5 2.1 0.3 2229.1 1.997 849.4 0.230 40.5 6.1 190 -3.6 -0.5 2.3 0.3 2219.3 1.988 842.0 0.237 41.7 6.1 195 -4.0 -0.6 2.4 0.3 2209.6 1.979 834.6 0.244 42.9 6.1 200 -4.3 -0.6 2.5 0.3 2199.9 1.970 827.3 0.251 44.1 6.1 205 -4.7 -0.6 2.7 0.4 2190.2 1.962 820.0 0.257 45.3 6.1 210 -5.2 -0.7 2.8 0.4 2180.5 1.953 812.8 0.264 46.5 6.2 215 -5.6 -0.7 2.9 0.4 2170.9 1.944 805.6 0.271 47.7 6.2 220 -6.0 -0.8 3.1 0.4 2161.3 1.936 798.5 0.278 48.9 6.2 225 -6.5 -0.8 3.2 0.4 2151.7 1.927 791.4 0.285 50.2 6.2 230 -7.0 -0.8 3.4 0.4 2142.1 1.919 784.4 0.292 51.4 6.2 235 -7.5 -0.9 3.5 0.4 2132.5 1.910 777.4 0.299 52.6 6.2 240 -8.1 -0.9 3.7 0.4 2123.0 1.902 770.5 0.306 53.9 6.2 245 -8.6 -1.0 3.9 0.4 2113.5 1.893 763.6 0.313 55.1 6.2 250 -9.2 -1.0 4.0 0.4 2104.0 1.885 756.8 0.320 56.4 6.3 255 -9.8 -1.1 4.2 0.5 2094.6 1.876 750.0 0.327 57.6 6.3 260 -10.4 -1.1 4.4 0.5 2085.1 1.868 743.2 0.335 58.9 6.3 265 -11.0 -1.2 4.5 0.5 2075.7 1.859 736.5 0.342 60.2 6.3 270 -11.7 -1.2 4.7 0.5 2066.3 1.851 729.9 0.349 61.4 6.3 275 -12.3 -1.2 4.9 0.5 2057.0 1.842 723.3 0.356 62.7 6.3 280 -13.0 -1.3 5.1 0.5 2047.7 1.834 716.8 0.364 64.0 6.3 285 -13.7 -1.3 5.3 0.5 2038.3 1.826 710.3 0.371 65.3 6.4 290 -14.5 -1.4 5.5 0.5 2029.1 1.817 703.8 0.378 66.6 6.4 295 -15.2 -1.4 5.7 0.5 2019.8 1.809 697.4 0.386 67.9 6.4 300 -16.0 -1.5 5.9 0.5 2010.6 1.801 691.0 0.393 69.2 6.4

24-Oct-20 06:32, JBM/jbmtraj-5.1.cgi

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[nick338]

200 YARD ZERO

Trajectory Input Data Ballistic Coefficient: 0.410 G1 Caliber: 0.224 in Bullet Weight: 77.0 gr Muzzle Velocity: 2600.0 ft/s Distance to Chronograph: 10.0 ft Sight Height: 1.50 in Sight Offset: 0.00 in Zero Height: 0.00 in Zero Offset: 0.00 in Windage: 0.000 MOA Elevation: 0.000 MOA Line Of Sight Angle: 0.0 deg Cant Angle: 0.0 deg Wind Speed: 7.0 mph Wind Angle: 90.0 deg Target Speed: 10.0 mph Target Angle: 90.0 deg Target Height: 12.0 in Temperature: 59.0 °F Pressure: 29.91 in Hg Humidity: 50 % Altitude: 800.0 ft Vital Zone Radius: 5.0 in Std. Atmosphere at Altitude: No Pressure is Corrected: Yes Zero at Max. Point Blank Range: No Target Relative Drops: Yes Mark Sound Barrier Crossing: No Include Extra Rows: No Column 1 Units: 1.00 in Column 2 Units: 1.00 mil Round Output to Whole Numbers: No Output Data Elevation: 6.189 MOA Windage: 0.000 MOA Atmospheric Density: 0.07402 lb/ft³ Speed of Sound: 1116.5 ft/s Maximum PBR: 313 yd Maximum PBR Zero: 266 yd Range of Maximum Height: 147 yd Energy at Maximum PBR: 674.7 ft•lbs Sectional Density: 0.219 lb/in² (yd) (in) (mil) (in) (mil) (ft/s) (none) (ft•lbs) (s) (in) (mil) Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead Calculated Table 0 -1.5 *** 0.0 *** 2607.1 2.335 1161.9 0.000 0.0 *** 5 -1.2 -6.6 0.0 0.0 2596.5 2.326 1152.4 0.006 1.0 5.6 10 -0.9 -2.4 0.0 0.0 2585.8 2.316 1143.0 0.012 2.0 5.6 15 -0.6 -1.1 0.0 0.0 2575.2 2.307 1133.7 0.017 3.1 5.7 20 -0.3 -0.4 0.0 0.0 2564.6 2.297 1124.4 0.023 4.1 5.7 25 -0.0 -0.0 0.0 0.0 2554.1 2.288 1115.1 0.029 5.1 5.7 30 0.2 0.2 0.1 0.0 2543.5 2.278 1105.9 0.035 6.2 5.7 35 0.4 0.4 0.1 0.1 2533.0 2.269 1096.8 0.041 7.2 5.7 40 0.7 0.5 0.1 0.1 2522.6 2.259 1087.8 0.047 8.2 5.7 45 0.9 0.5 0.1 0.1 2512.1 2.250 1078.8 0.053 9.3 5.7 50 1.1 0.6 0.1 0.1 2501.7 2.241 1069.8 0.059 10.3 5.7 55 1.3 0.6 0.2 0.1 2491.3 2.231 1060.9 0.065 11.4 5.8 60 1.4 0.7 0.2 0.1 2480.9 2.222 1052.1 0.071 12.5 5.8 65 1.6 0.7 0.3 0.1 2470.5 2.213 1043.4 0.077 13.5 5.8 70 1.7 0.7 0.3 0.1 2460.2 2.204 1034.6 0.083 14.6 5.8 75 1.9 0.7 0.3 0.1 2449.9 2.194 1026.0 0.089 15.7 5.8 80 2.0 0.7 0.4 0.1 2439.6 2.185 1017.4 0.095 16.7 5.8 85 2.1 0.7 0.4 0.1 2429.3 2.176 1008.9 0.101 17.8 5.8 90 2.2 0.7 0.5 0.2 2419.1 2.167 1000.4 0.108 18.9 5.8 95 2.2 0.7 0.5 0.2 2408.9 2.158 991.9 0.114 20.0 5.9 100 2.3 0.6 0.6 0.2 2398.7 2.148 983.6 0.120 21.1 5.9 105 2.3 0.6 0.7 0.2 2388.5 2.139 975.2 0.126 22.2 5.9 110 2.3 0.6 0.7 0.2 2378.4 2.130 967.0 0.133 23.3 5.9 115 2.3 0.6 0.8 0.2 2368.3 2.121 958.8 0.139 24.4 5.9 120 2.3 0.5 0.9 0.2 2358.2 2.112 950.6 0.145 25.6 5.9 125 2.3 0.5 1.0 0.2 2348.1 2.103 942.5 0.152 26.7 5.9 130 2.3 0.5 1.0 0.2 2338.1 2.094 934.5 0.158 27.8 5.9 135 2.2 0.5 1.1 0.2 2328.0 2.085 926.5 0.164 28.9 6.0 140 2.2 0.4 1.2 0.2 2318.0 2.076 918.5 0.171 30.1 6.0 145 2.1 0.4 1.3 0.2 2308.1 2.067 910.6 0.177 31.2 6.0 150 2.0 0.4 1.4 0.3 2298.1 2.058 902.8 0.184 32.4 6.0 155 1.8 0.3 1.5 0.3 2288.2 2.049 895.0 0.190 33.5 6.0 160 1.7 0.3 1.6 0.3 2278.3 2.041 887.3 0.197 34.7 6.0 165 1.6 0.3 1.7 0.3 2268.4 2.032 879.6 0.204 35.8 6.0 170 1.4 0.2 1.8 0.3 2258.5 2.023 872.0 0.210 37.0 6.0 175 1.2 0.2 1.9 0.3 2248.7 2.014 864.4 0.217 38.2 6.1 180 1.0 0.2 2.0 0.3 2238.9 2.005 856.9 0.224 39.3 6.1 185 0.8 0.1 2.1 0.3 2229.1 1.997 849.4 0.230 40.5 6.1 190 0.5 0.1 2.3 0.3 2219.3 1.988 842.0 0.237 41.7 6.1 195 0.3 0.0 2.4 0.3 2209.6 1.979 834.6 0.244 42.9 6.1 200 -0.0 -0.0 2.5 0.3 2199.9 1.970 827.3 0.251 44.1 6.1 205 -0.3 -0.0 2.7 0.4 2190.2 1.962 820.0 0.257 45.3 6.1 210 -0.6 -0.1 2.8 0.4 2180.5 1.953 812.8 0.264 46.5 6.2 215 -0.9 -0.1 2.9 0.4 2170.9 1.944 805.6 0.271 47.7 6.2 220 -1.3 -0.2 3.1 0.4 2161.2 1.936 798.5 0.278 48.9 6.2 225 -1.6 -0.2 3.2 0.4 2151.6 1.927 791.4 0.285 50.2 6.2 230 -2.0 -0.2 3.4 0.4 2142.1 1.919 784.4 0.292 51.4 6.2 235 -2.4 -0.3 3.5 0.4 2132.5 1.910 777.4 0.299 52.6 6.2 240 -2.9 -0.3 3.7 0.4 2123.0 1.902 770.5 0.306 53.9 6.2 245 -3.3 -0.4 3.9 0.4 2113.5 1.893 763.6 0.313 55.1 6.2 250 -3.8 -0.4 4.0 0.4 2104.0 1.885 756.7 0.320 56.4 6.3 255 -4.2 -0.5 4.2 0.5 2094.6 1.876 750.0 0.327 57.6 6.3 260 -4.7 -0.5 4.4 0.5 2085.1 1.868 743.2 0.335 58.9 6.3 265 -5.3 -0.6 4.5 0.5 2075.7 1.859 736.5 0.342 60.2 6.3 270 -5.8 -0.6 4.7 0.5 2066.3 1.851 729.9 0.349 61.4 6.3 275 -6.4 -0.6 4.9 0.5 2057.0 1.842 723.3 0.356 62.7 6.3 280 -6.9 -0.7 5.1 0.5 2047.6 1.834 716.8 0.364 64.0 6.3 285 -7.5 -0.7 5.3 0.5 2038.3 1.826 710.3 0.371 65.3 6.4 290 -8.2 -0.8 5.5 0.5 2029.1 1.817 703.8 0.378 66.6 6.4 295 -8.8 -0.8 5.7 0.5 2019.8 1.809 697.4 0.386 67.9 6.4 300 -9.5 -0.9 5.9 0.5 2010.6 1.801 691.0 0.393 69.2 6.4

24-Oct-20 06:31, JBM/jbmtraj-5.1.cgi

 

[natdscott]

This is actually a 2 part question. Where do users of this ammo zero their carbines and not sure I understand the 50/200 or 36/300 zero. I'm just used to "zeroing" the rifle at 200 yards and only being 1" or so high at 10 yards and everything else good in between.

I'm hearing people "zeroing" at 50 and having the path of the bullet cross again at 0.0 at 200 yards and this isn't making sense to me. My numbers on JMB are showing 4.3" drop at 200 when "zeroing" at 50.

I can simplify this for you, wayyyy “battle” close.

It’s 2 MOA from 0 yards to 100 yards.

It’ll be another 2 MOA from 100 to get to 200 yards.

3 Minutes from 200-300, 3 Minutes 300-400, etc..

2,2,3,3,4,4.. see the trend?

If you get used to that rule of thumb, you’re gonna make pretty good hits with standard cartridges.

If you get really used to that rule of thumb, and shoot around a lot of guys with different rifles, you can fudge elevation zeroes for faster/slower, slicker/fatter.

The rule I gave you was built around cartridges like the .30-06 and .308 with mid weight ammo. Turns out the AR, duh,...follows it pretty closely.

 

[jeffl838]

50/200 or 36/300 is more true for a bullet that flies closer to 3000 fps.

With the 77SMK and a 200m zero., you'll definitely have like two inches of hold under at max ord (125m ish)

At close quarters, you'll definitely have hold over relative to distance and height over bore. To visualize this, place your muzzle on the x ring at point blank, look through your optic (ideally a red dot) and see where your optic is pointing at... hypothetically, if you were shooting at point blank and aiming, you would have to put your dot THERE (probably 2.8 inches high) to hit the x.

Because eventually your trajectory (your line of bore and trajectory are very close at closer distances, so sometimes people describe this interchangeably) and line of sight intersect (maybe intersecting twice), you will have a hold over up until that first intersection. Sometimes your close quarters hold over matters - most of the time it doesn't.

 

[Neurotic]

If this is for an AR, the sight height should be 2.6" rather than 1.5". That'll push out the distance where the projectile crosses zero again.

 

[hypno02]

Here’s a good graphic explaining different ar15 zeroes. You need to adjust the sight height in your calculator to ~2.5”. Your sight height is the reason the rifle is zeroed at two different ranges. Every rifle is technically zeroed at two different ranges (assuming your sights are at 12:00 on the rifle) because the bullet crosses your sight path twice.

 

[LawnMM]

You're over complicating this. If you have a scope, zero at 100 and dial everything when you have time.

A 50/200 zero is just a trick of ballistics to use with iron sights and red dots so soldiers in combat can reasonably expect a hit while aiming center mass out to 2-300yds.

4" low on a center mass hold will still ruin a bad guys day.

As already stated, its an old rule of thumb and came about when 55gr ammo doing 3k+ out of a 20" barrel was common.

A 77gr bullet at 2300fps out of an SBR it's a bit less applicable.

Telling us what sort of sighting system you have and what kind of shooting you plan to do with it would help us point you in the right direction.

 

[nick338]

It's a Trijicon TA01 mounted on a 13.9" upper so dialing isn't an option.

 

[308pirate]

And this is what happens when you learn something without understanding the fundamental physics of what's going on.

You can't reason your way through the problem if any variable changes.

 

[308pirate]

It's a Trijicon TA01 mounted on a 13.9" upper so dialing isn't an option.

Learn how to use its reticle

 

[jeffl838]

Which reticle do you have? If you have the army spec one, if you zero your 100m hold at 200m, it actually lines up acceptably out to 500 out of a 14.5'' barrel. What velocity does your 13.9 launch the 77's at?

 

[nick338]

Which reticle do you have? If you have the army spec one, if you zero your 100m hold at 200m, it actually lines up acceptably out to 500 out of a 14.5'' barrel. What velocity does your 13.9 launch the 77's at?

It's the 5.56 BDC and mv is around 2600

Just playing with numbers if I zero at 250 the drop from 400-600 is identical to the reticle and no more than 3-4" off from 250 and in.

 

[jeffl838]

I used 200 because i defined my maximum acceptable margin of error as being 2.5 inches (accpeptable for the partial exposure of a face), but if you're ok with 3-4'' that sounds like the ticket

 

[BytorJr]

Don't laugh. I used my Strelock to set-up a zero at what probably is actually 275 yards. I meant to do a 30/300 setup but I think my target (what I thought was 30 was more like 26-27). Regardless, with a red dot, on an IPSC-C target making contact with steel at 100-380 yards is as simple as bottom of target for 100, top of target for 380. In between, bias slightly up/down. So for 200 I'm just a hair below the center and at 300 just a hair over the center. Not saying it's perfect, not saying it's what anybody else would do and I still may change it - but for a hurry up and get it mounted and "zero'd" it works. That setup is fast (to do and to use), covers a lot of target zones and makes the most of that 2MOA dot (Trijicon MRO).

Granted, with the 1/5 MOA adjustment it's a royal PITA most of the time to sight in (for me) and I've gone into how my Wheeler doesn't do well on brakes/flash-hiders.

 

[jeffl838]

Don't laugh. I used my Strelock to set-up a zero at what probably is actually 275 yards. I meant to do a 30/300 setup but I think my target (what I thought was 30 was more like 26-27). Regardless, with a red dot, on an IPSC-C target making contact with steel at 100-380 yards is as simple as bottom of target for 100, top of target for 380. In between, bias slightly up/down. So for 200 I'm just a hair below the center and at 300 just a hair over the center. Not saying it's perfect, not saying it's what anybody else would do and I still may change it - but for a hurry up and get it mounted and "zero'd" it works. That setup is fast (to do and to use), covers a lot of target zones and makes the most of that 2MOA dot (Trijicon MRO).

Granted, with the 1/5 MOA adjustment it's a royal PITA most of the time to sight in (for me) and I've gone into how my Wheeler doesn't do well on brakes/flash-hiders.

With a red dot you might be better off with something flying a little bit faster - 55 or 62 grains buzzing at over 3000 fps will really make that requirement you defined way easier.

 

[nick338]

I used 200 because i defined my maximum acceptable margin of error as being 2.5 inches (accpeptable for the partial exposure of a face), but if you're ok with 3-4'' that sounds like the ticket

I have an RMR for anything inside 200, so the 250 matched up with the reticle a little better than 200 provided the reticle is based on

55gr
3259 fps
.243 bc
2.5" sight height

I saw that posted somewhere and I won't have the sight until next week so I don't know if documentation that comes with it says something different.

 

[dms416]

The ACOG is all about simplicity which equates to speed and more hits on man-sized targets with the ammo/weapon/shooter equation that its meant for. Again, no sense over-complicating things.

FWIW, I've used M855 BDC's for Mk262 and the meter ranges for M855 match pretty close to the numbers if using yards. In other words, if the turret (in my case) is 600m (660ish yards), I'll be on a 2/3 IPSC @ 600y within a few inches of the water line. I know others have said they've used M118LR BDC's for shorter 308 gas guns when using Mk262 on SPR's.

Again, don't forget what an ACOG is.
I literally just watched a good shooter ride the struggle bus with a 4x ACOG during a DMR course for all of TD1. It seemed he was at a constant disadvantage regarding wind, UKD targets, KD targets not in his bdc reticle and locating/IDing shot-up steel at distance. Even with his 11.5" Colt, TD2 using the ai's loaner Mk5 HD 3-18, it was a complete world of difference. While goofy looking, he got to see (pun intended) what he was missing out on.

 

[Trigger Monkey]

The subtensions for the reticle were posted above and they're available on Trijicon's website. There shouldn't be any guesswork as to what the reticle is based on, you can plug your numbers into JBM and see where they fall along those subtensions. Easy peasy. Zeroed at 100, 2.6" SH, 2,000' DA, a 77 TMK @2600 fps will work out to this approximately. The below will get it done for most practical purposes.

0.0	100
1.7	200
4.6	302
8.3	407	~2" high at 400
13.0	522	~7" high at 500
18.9	640	~21" high at 600

 

[BytorJr]

With a red dot you might be better off with something flying a little bit faster - 55 or 62 grains buzzing at over 3000 fps will really make that requirement you defined way easier.

I am flying with 55g on the RDS. And, like I said, it seems to be working. I have not shot much "paper" or electronic to know much more than what I set on paper trying to accomplish 30/300 (or something there 'bouts) - and since I don't have a spotting scope I zero-in at 25 yards (less than ideal) for the "zero" that I want. However, when I can drive to my range, pop out the rifle, load up, and tag 380 yard IPSC-C without much thought other than hold at the top (for COM contact), I'm not really that interested in "fixing" it. Same for 100 yards in reverse. Is it perfect - hell no. Does it work (for me) - yes.

That said, my rangefinder comes this week. So, after hopefully everything calms down and the future is known - I may adjust again. Freaking red dot's always piss me off when sighting in...don't know why, but always. Scope...I can get close in 2-3 shots.

 

[308pirate]

It's the 5.56 BDC and mv is around 2600

Just playing with numbers if I zero at 250 the drop from 400-600 is identical to the reticle and no more than 3-4" off from 250 and in.

Imagine that

Problem solved

 

[nick338]

Imagine that

Problem solved

It wasn't really a problem to begin with. I knew beforehand that I was going to have to find a trajectory chart for the 77's that would get me close if I wanted to use the reticle. All I wanted to know was if other people were doing similarly or something different.

And I can't tell you how many times I've heard someone say zero your rifle at 36 or 50 and you'll be good at 300 and 200 respectively. Wanted to know how that was working out for them.

 

[308pirate]

And I can't tell you how many times I've heard someone say zero your rifle at 36 or 50 and you'll be good at 300 and 200 respectively. Wanted to know how that was working out for them.

I have my carbine RDS zeroed at 50 yards and confirmed all the way to 300 on 12x12 steel plates. To smack the 300 yard plate I need to put the dot on the top edge of it.

That's using Winchester White Box 62 gr OTM

 

[army_eod]

Strelok. Have to chrono yer boolets.