Zeroing a new 308 win

[AJC1]

1.75 minutes (7 clicks) from 100 to 200yrds is about exact on my 308.
Added, I zero this one at 100

You would be in the up part of the trajectory vs the down.

 

[stringnut]

Here's a question; If sighted 1.75 above the 100 yard mark, would the trajectory cause a shooter to be above the animal at shorter ranges? Say 25 -50 yards??

No. Depending on the height of the reticle above the center of the bore you will be dead on to 1 inch low at 25 yards. Your question is good one as understanding trajectory helps you know what is , or isn’t, a reasonable shot.

Everyone says bullets travel in an arc. It is more like half of a parabola and a tilted one at that. You can actually think of it as a slope that continually gets steeper. The farther out you are the more the bullet drops per distance traveled. Your vision thru the scope is in a straight line. What this means is that is your line of sight and bullet impact are only the same at a couple of yardages. Ballistic charts available on line from various ammo and reloading suppliers show this quite well.

For example my 250 Savage at 2750 fps with a 100 gr Sierra pro hunter. Sighted in dead on at 200 yards means it hits just over 1.5 inches high at 100 yards. It is about dead on at 50 yards. At 150 yards it is around 2 inches high. After that I don’t know as that is the farthest I have shot targets with it. These dimensions are from actually shooting at these ranges. Have shot deer from 9 feet to about 225 yards and there is no worries about the bullet being to high or too low.

 

[Dr T]

The Hornady website has a nice little tool for playing with this. See https://www.hornady.com/team-hornady/ballistic-calculators/#!/

Use the standard ballistic calculator, look up the balllistic coefficient of a bullet that is close to what you are using (say, 0.39, the thousandths don't really matter for your application), and get the trajectory from 0 to 500 yards in 25 yard increments.

(OP stated that he was looking at shots out to 200 to 250 yards with 100 being the most common range...)

At longer ranges and very high ballistic coefficients other rules apply.

 

[Skylerbone]

Here's a question; If sighted 1.75 above the 100 yard mark, would the trajectory cause a shooter to be above the animal at shorter ranges? Say 25 -50 yards??

Shooting .308 you’d be about 3/4” high at 50 yards and probably just a tad under at 25 yards (depending of course on load).

 

[JFrank]

Shooting .308 you’d be about 3/4” high at 50 yards and probably just a tad under at 25 yards (depending of course on load).

I missed a Lion last year at about 20 yrds by what couldn't have been more than an inch, man that had my heart pumping. That was my 30-30 zeroed at 100, it shoots about the size of a baseball if im lucky.. Anyway this thread made me recall that cat.

 

[H&Hhunter]

Here's a question; If sighted 1.75 above the 100 yard mark, would the trajectory cause a shooter to be above the animal at shorter ranges? Say 25 -50 yards??

Absolutely not… With a 200 yard zero you’ll be close enough to on the cross hair at 25 or 50 yards that it will not matter.

 

[wombat13]

Dr. T posted the link. We don't really have to guess (of course one should shoot to confirm since one's rifle is unlikely getting the exact advertised MV). Federal indicates the OP's load has MV 2,820 fps and BC 0.313. Sighting in 1.5" high at 100 yards gives the following elevations (Yards/elevation): 25/-0.3"; 50/0.6; 75/1.2; 100/1.5; 125/1.4; 150/1; 175/0.2; 200/-1; 225/-2.6; 250/-4.7"

 

[Dr T]

And I gave 1.5" to 1.75" since for most scopes in the US 1 click = 0.25" at 100 yards.