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Ventured into the 308 realm. Read on the webs that a 25 yard zero was the way to go. While validating it today I was 4” high at 50 and nearly 8” high at 100. Even higher at 150.
I run a 50 yard zero on all of my red dot 5.56 guns and it works perfectly to 300 yards for me. Most of my competitions are run and guns with 10” plates.
This zero will not work for me. This is a 16” bbl and red dot. What do you all recommend?
I zero mine 1" high at 100 yards. I did this because it is the zero my manual calls for my BDC to be accurate. Primary Arms 1-8X.
For a red dot I would either use a 100 yard or 50 yard zero. If 50 works for your 556 guns, it will be almost identical for 308. The two bullets have a very similar trajectory. 25 is a rainbow trajectory. Really stupid for anything but a COM hits out far. No precision at all.
I do a 50/200. I run a Trijicon MRO on my Colt CM762, and it fairs excellent even out to 250 or so. Just depends on what you’re going for.
Between 200 yds zero, and a 300 yard shot I only have to adjust 3 moa.
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The zero will vary based on the optic you are using. If it is a low power variable optic or another magnified optic, a 100yd zero is preferred, but also pay attention to what that optic's user manual says. If it is a red dot, first ask yourself why you are using this type of optic for a caliber that is designed for 300 to 600 yard or longer engagements and what benefit a red dot would give you. If you still plan to go this way, a 100yd zero is again the preferred zero, but you could get away with a 50/200.
What's your intended use and range-distance?
A zero's not a zero for your intended use until you've shot and verified it -- otherwise it's just "Close."
This, and:Quote:
Originally Posted by sinister
What ammo are you shooting?
7.62/.308 is fairly different than 5.56 when comparing the trajectory paths inside 100, and how that turns out at longer distance.
How much that matters is up to you.
I have played around with a few different zeroing methods for 16" 7.62, with purposes between USCA Match performance, PRS Gas Gun performance, hog/medium sized mammal hunting, and general purpose carbine stuff. While a lot of these share common concepts, there
Here's a quick close range trajectory comparison with SMK 175gr with a 16" barrel (2500f/s) at 0 DA and a 3.25" high LOS over bore (1.94" mount) between a 100 yard zero and a 200 yard zero:
100 yd POA/POI:
Range (y): Elevation (inches) 100yd/200 yd
5: -2.94 / -2.86
10: -2.64 / -2.48
15: -2.36 /-2.12
20: -2.09 /-1.77
25: -1.84 /-1.44
30: -1.60 /-1.12
35: -1.38 /-0.82
40: -1.17 /-0.52
45: -0.97 /-0.25
50: -0.79 /0.01
55: -0.63 /0.26
60: -0.48 /0.49
65: -0.34 /0.70
70: -0.22 /0.90
75: -0.12 /1.09
80: -0.03 /1.26
85: 0.04 /1.41
90: 0.10 /1.55
95: 0.14 /1.67
100: -0.00 / 1.61
105: 0.00 / 1.69
110: -0.01 / 1.75
115: -0.05 / 1.80
120: -0.09 / 1.84
125: -0.16 / 1.85
130: -0.24 / 1.85
135: -0.33 / 1.83
140: -0.45 / 1.80
145: -0.59 / 1.74
150: -0.73 / 1.68
155: -0.90 / 1.59
160: -1.09 / 1.48
165: -1.29 / 1.36
170: -1.51 / 1.22
175: -1.75 / 1.06
180: -2.00 / 0.89
185: -2.28 / 0.69
190: -2.57 / 0.48
195: -2.88 / 0.25
200: -3.21 / 0.0
*These numbers do change a bit with a lower mount, and with different ammunition/velocity
Difference between highest to lowest POI from 0 to 200 yards: 3.35"/ 4.71"
Distance range with 1.5" of deviation in POI: 130 yards (35 yds to 165 yds) / 145 yards (60 yds to 205 yds)
POI change from 5 yards to 50 yards: 2.15" / 2.85"
POI change (highest point to lowest point) from 50 yards to 150 yards: 0.93" / 2.1"
The next big set of numbers that matter is between 200 and 500, but that depends a lot on application and target size.