Brain teaser for the day...

[fayettefatts]

Here's my logic.

The bullet follows the bore reguardless of where the sights are pointing. If you cant the rifle to the right, around the axis of the bore, the sights move right and down. When you re-align the sights on the target, the barrel is moved left and up. Again, the bullet follows the bore and impacts high and left.

 

[Henryp]

Let's stop guessing and think. If it is canted 90 degrees right, the barrel is horizontal and aimed to the right. It will hit low right. Half way will be about half as much. If rotated 180 degrees, it will shoot very low.

 

[Erik Cortina]

Here's my logic.

The bullet follows the bore reguardless of where the sights are pointing. If you cant the rifle to the right, around the axis of the bore, the sights move right and down. When you re-align the sights on the target, the barrel is moved left and up. Again, the bullet follows the bore and impacts high and left.

How do you use the bore axis to aim? We use the scope to aim, thus, the bullet will impact opposite of where you think, which is low and right.

 

[fayettefatts]

Here's my logic.

The bullet follows the bore re guardless of where the sights are pointing. If you cant the rifle to the right, around the axis of the bore, the sights move right and down. When you realign the sights on the target, the barrel is moved left and up. Again, the bullet follows the bore and impacts high and left.

How do you use the bore axis to aim? We use the scope to aim, thus, the bullet will impact opposite of where you think, which is low and right.

Think of it this way. A barrel with sights attached to the top is placed in v-blocks and sighted in. The barrel & sights are then canted to the right. The sights are now pointing low and right, yet if another shot is fired, it will still impact the same place as the barrel hasn't moved. Now if you move the v-blocks to align the sights properly, the barrel will also be moved in the same direction which is left and up. Where will the bullet impact now??

 

[Henryp]

The barrel has max elevation when vertical. Any cant will lower aim point and hit the direction canted.

 

[DCRYDER]

I wish someone would go out and prove this. Heck it could be done with a 22lr at 100 yards. I would but it's -8* here today.

Yes, when you cant it to the right then reposition the crosshairs onto the target your barrel will be moving low and left. BUT it will still be pointing towards the crosshairs and the bullet will intersect the crosshairs the first time probably within 10 or 20 yards from the muzzle. Now since the muzzle is left off the target, then crosses the crosshairs, continues on its path it has to keep going to the right.

Now take a 3' yard stick. Holding it vertical with one end on the floor. The other end is 3' from the floor. Now lean the stick 45*to the right,. Is the top of the stick still 3' from the floor? I think not.

 

[Toby Bradshaw]

Think of it this way. A barrel with sights attached to the top is placed in v-blocks and sighted in. The barrel & sights are then canted to the right. The sights are now pointing low and right

If the scope axis and the the barrel axis are parallel, then this is true. But in real life the scope axis is not parallel to the bore axis.

Here's a question that follows from your logic: If the rifle is turned upside down, rotated around the axis of the bore, where will the scope be pointing on the downrange target? Keep in mind that the scope axis and bore axis converge -- they aren't parallel.

 

[fayettefatts]

Think of it this way. A barrel with sights attached to the top is placed in v-blocks and sighted in. The barrel & sights are then canted to the right. The sights are now pointing low and right

If the scope axis and the the barrel axis are parallel, then this is true. But in real life the scope axis is not parallel to the bore axis.

Here's a question that follows from your logic: If the rifle is turned upside down, rotated around the axis of the bore, where will the scope be pointing on the downrange target? Keep in mind that the scope axis and bore axis converge -- they aren't parallel.

tobybradshaw: The way you explain it makes sense. Perhaps my logic is flawed! The angle of bore/sight plays more of a roll than I initially thought. When my brain quits hurting, I may have to change my vote.

 

[Blaster-37]

Guys,
The barrel trajectory was pointed above the scope line of sight to get a heavy 308 to 1000 yards. We rolled the scope 45 degrees right and kept it centered on target. The trajectory now went from 12:00 to 1:30. Now the barrel is pointed right of the line of sight.
By turning the scope and keeping it on center we lose the elevation or "trajectory". This "trajectory" now becomes a huge windage right beyond the line of sight to center. We also no longer have the vertical trajectory to get it there, it now becomes a dying quail quickly. It started at the target line and continued right from the line. Without some huge windage adjustment into a left wind originally, how could it get higher when rolled 45 degrees right?
I am sure I am not articulating this very well, bear with me.
How did it get left and how would it get higher than the original trajectory, ever?
Low and Right. Please correct me.
Greg

 

[Nomad47]

I wish one of you guys saying high and left would make a huge bet with me.

Like someone said, it is easy to prove at just about any range.

 

[wolley]

Changing to low right.

 

[jasmine2501]

Like someone said, it is easy to prove at just about any range.

You can prove it by holding a triangle up in the air. It should be obvious what will happen. I think the confusion here is over the definition of "right" rotation. If the rotation is clockwise from the shooters perspective, and the sights remain aligned, the barrel is now pointing low and right. (and if you go the other way it will still be low, but now left)

 

[Erik Cortina]

Jasmine2501, welcome to the forum. It must feel great to be right starting from post #1! ;D

 

[jasmine2501]

Jasmine2501, welcome to the forum. It must feel great to be right starting from post #1! ;D

LOL, thanks. I'm mostly an AR shooter, but I'm getting into long range stuff. I joined this site because the AR site offended me on first look. Everyone here seems nice and friendly and interested in being better shooters, not sniping at each other. I want some help with my AR build though, I'll post about that later.

 

[GSPV]

If you read carefully, there are three kinds of answers here, the ones that define can't as around the axis of sight, the ones that define cant as around bore axis and those that are just plain confused.

The only thing that makes sense to me is cant about line of sight. In that case, the new POI will be low/right.

 

[KenO]

OK, I'm a convert to low right also. I missed in my mind that the axis of the sights is actually under the barrel since the trajetory is above the sights.

 

[Immike]

In a BW video, "How to dope the wind", in the David Tubbs segment on rifle cant, they cant a rifle 5-degrees at 600yds from a Tubb2000 with 115-DTAC bullets. Starting with the gun zero'd in the X-ring, they cant the rifle to the right, the POI on the target was about 18"-right and about 2"-lower.
Next they do the same with a left cant, and the results are almost identically but to the left opposing side, 18"-left and 2"-low.
Next they level the gun and the POI is a dead center hit in the X-ring.
Using the same point of aim for all (the X in the target X-ring).

Excellent post!! Now we are going somewhere with this!! I keep a eye on my offset level on my scope at all times and constantly keep it as close as possible while I shoot, it's a must !!

 

[Erik Cortina]

I'm glad this thread has taken the course that it has. It will be an eye opener for many shooters that do not keep a constant eye on their levels when shooting long range. It will also help troubleshoot a wild shot.

 

[Immike]

Mr Moran is making some excellent points that need to be understood if you want to gain in competition. If you are wrestling with the rifle it is enough to knock you out of the top slots in a match against people that have it together.

 

[Blaster-37]

Donovan's drawing at the beginning of this, page 1, left little doubt of the correct answer. Visual aids are great, for most folks.
Good job Donovan.
greg