How to sight in with a new scope?

Bronco Boy

Bronco Boy

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Center fire hunting rifle: Let’s assume you are on the paper at 25 yards and the goal is to get to 1.5 to 2 inches high at 100 yards.

So you take a shot at 25 yards and are on the paper but 7 inches high and 4 inches right. What next?


What is the correct procedure for sighting in a firearm with a newly scope for general hunting purposes?
 
zero for 25,zero for 50 then zero for 100.
Then up 12 to 16 clicks assuming it's a 1/8 click adjustment
 
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With your example and with a scope where each click equals 1/4 inch (at 100 yds), you would turn the top turret down 28 clicks and the windage turret left 16 clicks to get a zero at 25 yds. This would put you on zero at 25 and should be confirmed by shooting again at 25.

If all is well, move your target to 100 yds and shoot a 3 shot group. The center of this group should be slightly high. Make necessary adjustments and shoot a second group to confirm.

When I soght my .270 Win so it's dead on at 25 yds, it usually groups about 3" high at 100 yds.
 
Here is a surefire way to Zero your rifle. If your 7" high and 4" right after 2 shots, lock your rifle to your POA and dial your elevation and windage turrets (or have a friend dial them in so you can hold the rifle from moving) to the POI. Take another shot at your target and you should be almost dead on.

Chances are good that when you get Zeroed at 25 you may be right where you want to be at 100.

Zero at 25, shoot 2-3 @ 50 to make sure your windage is correct then shoot 3-5 at 100. As the bullet is still on it's way up to the top of it's trajectory at 25 I usually end up 2-3 inches high at 100 with my .223 and 6BR.
 
CyaN1de said:
As the bullet is still on it's way up to the top of it's trajectory at 25 I usually end up 2-3 inches high at 100 with my .223 and 6BR.
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Ahhhhhh Starting to make sense. I was pretty baffled when trying to site in my 22-250 today. I had it about 2.5 inches high at 50 yards and when I shot my 100 yard target it was almost 5 inches high. I was like WTF? I did not have a clue what to do. I should have zeroed at 50 before trying the 100 and not left it high.

How do I find out the "path" of a particular round? Obviously the 22-250 is climbing between 50 and 100. When would it start to descend?
 
Bronco Boy said:
Ahhhhhh Starting to make sense. I was pretty baffled when trying to site in my 22-250 today. I had it about 2.5 inches high at 50 yards and when I shot my 100 yard target it was almost 5 inches high. I was like WTF? I did not have a clue what to do. I should have zeroed at 50 before trying the 100 and not left it high.

How do I find out the "path" of a particular round? Obviously the 22-250 is climbing between 50 and 100. When would it start to descend?
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As soon as a bullet leaves the barrel, it is descending. Lots of things to try and explain, but here is a write up that you might find useful.

http://www.chuckhawks.com/bullet_trajectory.htm
 
As stated above your bullet drops immediately, it never really ascends, but it can appear to ascend. Picture a curved line as the path of your bullet but since your scope is about 1"-2" or so above your bbl in order for your scope to line up with let's say the 200yd mark it has to pass through the line your bullet makes.
In the case of a 22-250 a zero at 200 is usually also dead on at around 50yds and your sight path will be low and there fore the bullet hits "high" at 100yds.
Trajectory is based on your veolcity a faster bullet will drop less over x amount of distance, your bullet shape will also come into play as it is affected by air resistance..

Now the other rifle guys can chime in here, does bullet weight also play a factor? I know in a perfect air free environment it would not, as gravity has the same effect on everything.

When sighting in, you also have to take in to account your scope height but as long as you try various distance you will know where she shoots.

With my 22-250. I am pretty confident that from 50-200 yds on coyote sized game, I do no thave to hold high or low. at less than 50 yds, I will hold a bit high to compensate for the height of the scope but only for shooting smaller targets as it will be within an inch and a half.
 
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Bullet weight does indeed influence trajectory. there are bullet drop charts out there, but they are at best approximations. There is no substitute for actual firing at various distances and noting the drop. In a hunting rifle, zero at 25, move to 100 and check zero. For big game, I find 2-3 inches high at 100 works the best for most of the calibers I use. For varmint calibers, 1.5 inches high is plenty. Then begin work on your own drop chart at any distance you would think of shooting at an animal at. Note the drop, make a small reference card and tape it to the buttstock of your rifle. EG: +3"@100, +1.5"@200, 0@270, -3"@300, etc. - dan
 
dan belisle said:
Bullet weight does indeed influence trajectory. there are bullet drop charts out there, but they are at best approximations. There is no substitute for actual firing at various distances and noting the drop. In a hunting rifle, zero at 25, move to 100 and check zero. For big game, I find 2-3 inches high at 100 works the best for most of the calibers I use. For varmint calibers, 1.5 inches high is plenty. Then begin work on your own drop chart at any distance you would think of shooting at an animal at. Note the drop, make a small reference card and tape it to the buttstock of your rifle. EG: +3"@100, +1.5"@200, 0@270, -3"@300, etc. - dan
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I often wondered if it was bullet weight affecting the drop or if bullet weight affects the velocity and therefore the drop.

Would 2 bullets of the exact same dimensions, but lets say 30 gr in the difference, travelling the same velocity hit in completely different spots?
For me, I shoot a 45gr JHP around 3900 fps and a 50 gr Vmax around 3700 fps and they hit almost exactly in the same place (at 100) with the VMax making a smaller group now that's only 5 gr.
 
Barrels vibrate when fired, for exaggerated clarity picture a car antenna whipping around. Different bullets will cause different vibrations and will usually exit the muzzle when the barrel is in a different position. It can be when the muzzle is at it peak, lowest point or anywhere is between. Use the same ammo for sighting in and hunting. Yes, sometimes there is a huge difference in POI.

The best method is to use a gun vise.
Note the weather conditions, especially wind strength and direction. Walk the range to feel it all the way to the target, you may be surprised.
Fire a shot, preferrably using a rest.
Place the rifle in the vise and aim it at the bullseye.
Carefully adjust the crosshair to the bullet hole.
Then in your case, adjust the crosshair 1" LOWER.
Remove the rifle from the vise and fire a 5 shot group, let the barrel cool between shots.
Set the rifle in the vise.
Adjust the crosshair to the middle of the group.
Fire a group at 300, which is the furthest you should shoot game at unless specifically train for.
Do not chase the bullseye around, the rifle will shoot a pattern not a tiny one hole group.
 
I'm amazed that folks havent sorted out this "bullet drops immediately" thing. Bullets begin to accelerate downward immediately upon barrel exit , at a rate of 32.2 ft/sec2. For a typical 200 yard zero shot from a horizontal rest, the bullet exits the barrel in a slightly upward trajectory. The upward component of velocity is affected by acceleration causing it to begin to arc in a downward direction. At some point, around 100y, it reaches its apogee (highest point), and actually begins to fall.
Many hunters try to exploit the rise and fall to minimize error over the range of distances they shoot. Using the above example, with an average shooting range of 100 y, setting to a 200y zero gives you an error band of about 2 in between 50 and 200y. If you set the scope to a 100 y zero, then that band increases to about 4 inches over the 50 to 200 y range. (The above numbers are based upon a typical 30 cal...)
 
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dan belisle said:
Bullet weight does indeed influence trajectory. there are bullet drop charts out there, but they are at best approximations. There is no substitute for actual firing at various distances and noting the drop. In a hunting rifle, zero at 25, move to 100 and check zero. For big game, I find 2-3 inches high at 100 works the best for most of the calibers I use. For varmint calibers, 1.5 inches high is plenty. Then begin work on your own drop chart at any distance you would think of shooting at an animal at. Note the drop, make a small reference card and tape it to the buttstock of your rifle. EG: +3"@100, +1.5"@200, 0@270, -3"@300, etc. - dan
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Sorry bro, but bullet weight makes no difference to the universal acceleration due to gravity. If a heavier bullet has a different trajectory than a lighter bullet it is for one of two reasons (or both reasons):


1. The bullet has a different ballistics coefficent.

2. The bullet leaves the rifle with a different velocity.

If you can fire a heavier bullet at the same muzzle velocity as a lighter bullet and they both have the same ballistics, there will be no difference in trajectory.
 
OK, so now I'm really confused about bullet drop/trajectory.

According to "the local gun shop guru" I stopped in to chat with the bullet does indeed climb before beginning to fall.

I'm going back to the range (right now) and I'm going to zero at 50 and see where is at 100, 150 and 200.
 
Shrek said:
Sorry bro, but bullet weight makes no difference to the universal acceleration due to gravity. If a heavier bullet has a different trajectory than a lighter bullet it is for one of two reasons (or both reasons):


1. The bullet has a different ballistics coefficent.

2. The bullet leaves the rifle with a different velocity.

If you can fire a heavier bullet at the same muzzle velocity as a lighter bullet and they both have the same ballistics, there will be no difference in trajectory.
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I stand by what I said. The bullet weight will affect trajectory. Different weight bullets usually have 1) a different ballistics coefficient (although you can match a few fairly closely) and 2) different weight bullets almost always leave the firearm at different velocities. I can't get a 207 gr Amax out of my 308 at the same speed as a 178 gr Amax. While I didn't go into any great detail over why the different weights affect things, they do. Basically, we're not disagreeing here, we're just looking at the results from two different angles. - dan
 
Bronco Boy said:
OK, so now I'm really confused about bullet drop/trajectory.

According to "the local gun shop guru" I stopped in to chat with the bullet does indeed climb before beginning to fall.

I'm going back to the range (right now) and I'm going to zero at 50 and see where is at 100, 150 and 200.
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Bullets do not climb. Period. If you look at your gun from the side, the scope would be level, and the barrel would be angled such that the bore is pointed slightly upwards in comparison. This is what makes people think the bullet climbs. If your bore was level, it would start dropping immediately upon leaving the bore, at first microscopically, but at ever greater amounts as the bullet loses speed. - dan
 
Dan - In your example, the barrel is slightly canted upwards. This imparts an upward component of velocity to the bullet - if the cant is sufficient, the bullet will cross the line of sight - twice, once rising, once falling - as you would toss a coin in the air.
Is that not climbing? Please elaborate?
 
cosmic said:
Dan - In your example, the barrel is slightly canted upwards. This imparts an upward component of velocity to the bullet - if the cant is sufficient, the bullet will cross the line of sight - twice, once rising, once falling - as you would toss a coin in the air.
Is that not climbing? Please elaborate?
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The bullet may climgb relative to the shooter but it does not climb relative to the bbl.
If the bbl is pointe up the bullet climbs, if it is level it drops immediately.

In the end if you consider your scope to be the refence point, then yes it climbs, if your rilfe is the reference point then no it does not climb.
 
In relationship to the ground you may think the bullet is climbing but it is only because you pointed the rifle higher when it was fired.. then the bullet in relationship to the elevated barrel begins to fall as soon as it exits the barrel and continues to fall until it hits something.

In order for a bullet to truly climb would require it to be a rocket with it's own power.

Rifle scopes and iron sights are mounted so when they are "level" the barrel is pointing slightly "up".
 
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