.308 win and 7.62x51 trajectory w/ 50 yard sightin

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jeepman4804

New member
Looking for some guidance on this matter. I want to use a 50 yard sight-in on my newest .308 ar but would like to know what I can expect trajectory wise until I can confirm in via paper. I plink with surplus 7.62x51 and will be shooting 168grain .308 for killin stuff.

With a 50 yard sight-in and standard height iron sights what would my poa/poi be a 25 yards (all I have till Saturday)?

I know some of you are genius with this stuff so any insight will help.
 
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Rimfire5

New member
With a 168 grain bullet and 2650 fps muzzle velocity (Federal Match with Sierra Match Kings) and your scope center 1.5 inches above the barrel center, sighting in your zero at 50 yards would mean that the round would be
0.59 inches low at 25 yards,
0.14 inches high at 100 yards
1.27 inches low at 150 yards
4.44 inches low at 200 yards.

You didn't say what weight the plinking ammo was or what the muzzle velocity was.

If the plinkers were 147 grains at 2550 fps, and a 50 yard zero, the plinking ammo would be
0.57 low at 25 yards
0.04 high at 100 yards
1.65 low at 150 yards
5.12 low at 200 yards.

I hope that helps.
 
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jeepman4804

New member
Plinkers are the 147 gr variety. And that helps a bunch! Thanks.

1 more quick question. The barrel I have is 1 in 10 twist... Think I should experiment with a little heavier projectile?
 
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PawPaw

New member
Interesting question. The old timers would tell you that a 25 yard zero will put you close enough in the ball park to kill game out past 200 yards.

So, I got out my ballistics calculator and found the folllowing interesting fact about my .30-06 hunting load.

2900 fps, .30-06, 150 grain Nosler Ballistic Tip

25 yards. - 0.00
50 yards - +1.20
100 yards - +2.78
150 yards - +3.16
200 yards - +2.24
250 yards - 0.00
300 yards - -3.80 inches.

That's very interesting, and is purely theoretical, but I've found that this program closely approximates what I see in the field.

1 more quick question. The barrel I have is 1 in 10 twist... Think I should experiment with a little heavier projectile?
Click to expand...

Naah, 1:10 is standard for .30 caliber in this country. It'll shoot those weights just fine.
 
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jeepman4804

New member
.308 Win. Hornady TAP FPD 168 Grain 2700 fps is what I will be using on a regular basis. If that helps any. I am very new to the .308 world.

I have a .556 for work and my deer guns are .243, .270, and my 30-06 gets the most use. I am just now getting into the longer range interests as 150yards and under is just plain boring now.
 
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PawPaw

New member
I am just now getting into the longer range interests as 150yards and under is just plain boring now.
Click to expand...

If you get out past 150 yards, none of this might be any good. This is all theoretical and there's nothing like actually testing your skill at the ranges you'd like to use them. A 50 yard zero should put you on paper, but for longer work, a good sight-in is critical. The ballistics tables would help, but there's nothing like actually shooting at those ranges.

Unless I'm sadly mistaken, the military is now using 175 grain Matchkings for long-range work in the 7.62 round. They find it carries better at long ranges.
 
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