Here is some data compared against various 5.56 and 6.8 SPC loads. Drop is expressed in inches. All assume 2.5" site over bore, 60F, sea level altitude, 30 Hg Pressure. Velocities used for 5.56 and 6.8SPC rounds assume 16" barrel while 300blk assume 9".
Distances in yards:------------------------------> 0 | 25.0 | 50.0 | 75.0 | 100.0 | 125 | 150 | 175.0 | 200 | 225 | 250.0 | 275 | 300 | 325 | 350 | 400.0
1) 75 grain TAP T2 at 2750 fps 25 yard zero: -2.5 | 0.00 | 2.20 | 4.09 | 5.66 | 6.88 | 7.75 | 8.25 | 8.36 | 8.06 | 7.33 | 6.15 | 4.51 | 2.37 | -0.28 | -7.25
2) 75 grain TAP T2 at 2750 fps 50 yard zero: -2.5| -1.10 | 0.00 | 0.79 | 1.25 | 1.38 | 1.15 | 0.54 | -0.45 | -1.85 | -3.68 | -5.96 | -8.70 | -11.9 | -15.7 |-24.86
3) M855 at 3000 fps 25 yard zero---------->: -2.5| 0.00 | 2.25 | 4.23 | 5.93 | 7.34 | 8.43 | 9.19 | 9.60 | 9.64 | 9.30 | 8.53 | 7.33 | 5.66 | 3.49 | -2.46
4) M855 at 3000 fps 50 yard zero---------->: -2.5| -1.12 | 0.00 | 0.86 | 1.44 | 1.72 | 1.68 | 1.32 | 0.61 | -0.47 | -1.94 | -3.83 | -6.16 | -8.95 | -12.3 | -20.4
5) 110 grain TAC-TX at 2150 25 yard zero->: -2.5| 0.00 | 2.00 | 3.47 | 4.37 | 4.67 | 4.31 | 3.24 | 1.43 | -1.19 | -4.67 | -9.09 | -14.5 | -21.0 | -28.7 | -47.7
6) 110 grain TAC-TX at 2150 35 yard zero->: -2.5| -0.62 | 0.77 | 1.62 | 1.91 | 1.59 | 0.61 | -1.07 | -3.50 | -6.73 |-10.8 | -15.9 | -21.9 | -29.9 | -37.3 | -21.9
7) 110 grain TAC-TX at 2150 50 yard zero->: -2.5| -1.00 | 0.00 | 0.47 | 0.37 | -0.34 | -1.7 | -3.76 | -6.58 | -10.2 |-14.69 |-20.1 | -26.52 | -34.0 | -42.7 | -63.75
8) 110 grain TAC-TX at 2150 100 yard zero>:-2.5| -1.09 | -0.18 | 0.19 | 0.00 | -0.80 | -2.26 | -4.41 | -7.32 | -11.0 | -15.6 |-21.1 | -27.63 | -35.2 | -44.0 |-65.23
9) 110 grain Horn VMAX 6.8 at 2550 25 yards:-2.5 | 0.00 | 2.15 | 3.94 | 5.34 | 6.34 | 6.92 | 7.05 | 6.72 | 5.89 | 4.54 | 2.65 | 0.18 | -2.90 | -6.62 | -16.1
10) 110 grain Horn VMAX 6.8 at 2550 50 yards:-2.5 |-1.08 | 0.00 | 0.71 | 1.04 | 0.96 | 0.46 | -0.48 | -1.89 | -3.79 | -6.22 | -9.18 | -12.73 | -16.88 | -21.68 | -33.34
As you can see, a 50 yard zero with the TAC-TX gives you a very flat trajectory (POA +/- 1") out to about 130 yards. On the other hand, a 25 yard zero allows you to use POA with no hold over out to 250 yards or so, but the trajectory inside of 100 yards can vary up to 4". So, I suggest using a 50 yard zero if you are looking for distances out to 100 yards. Use a 25 yard zero if you envision the gun being used beyond 100 yards, but be willing to accept up to a 4" error for CQB use.
I hope that this helps.
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