Scope Leveling; Instruction that ran counter to everything I thought I knew

[IBA_270]

Super interesting exchanges here. FWIW...the Applied Ballistics app can account for cant (offset) if I'm not mistaken...

I had no idea my 6th post would start this. Sorry about that...

 

[omicron1792]

I will try to explain cant quickly. Using extremes.

The bullet leaves the barrel 1.5”-2.75” under your scope. Most rifles are set up between 1.75-2.25”. That is significant. We are not shooting laser beams. We are shooting a bullet that leaves the rifle and immediately pulled by gravity in an arch until it stops.

If you took your rifle and laid it on its side with a 90 degree cant and dialed 8.4mil on your scope for a 1000yd target. Would you expect to hit your target? Absolutely not. Even if you had perfect fundamentals and great npa you will miss your target by a lot.

Well now break the same shot with a 45deg cant…you will still miss by a ton. Now try 15deg cant. Still missing. As you get closer to 0deg can’t you will start seeing less drift on your POI.

This is just basic physics.

That’s not exactly right.

Many mount a red dot or second optic on 45 or 90 offset from gun being up right. Doesn’t matter at all.

If you laid your gun on its side, and mounted th me scope at 90 degrees, then the bullet would still behave with regards to gravity, not the orientation of the gun to the ground. Think of a gangster turning pistol to the side as he shoots.

I’m not saying it’s the best way to do it. But as long as the reticle is plumb with regards to up and down then the bullet will behave the same when it leaves the barrel.

 

[omicron1792]

What about windage?

Wind would affect the bullet the same regardless of the roll of the rifle. And your windage changes on scope would do the exact same thing as long as your scope is level to the ground.

See this picture. Special forces offset optics all the time. The bullet is still shooting straight and dropping towards the earth curve.

 

[IBA_270]

That’s not exactly right.

Many mount a red dot or second optic on 45 or 90 offset from gun being up right. Doesn’t matter at all.

If you laid your gun on its side, and mounted th me scope at 90 degrees, then the bullet would still behave with regards to gravity, not the orientation of the gun to the ground. Think of a gangster turning pistol to the side as he shoots.

I’m not saying it’s the best way to do it. But as long as the reticle is plumb with regards to up and down then the bullet will behave the same when it leaves the barrel.

That was a point I was going to make...er...ask; if you take a barreled action and clamped to a table and fired it, then rotated it 90 degrees, then rotated...the bullet will perform exactly the same. It won't land in the same spot of course, that's why we zero the optic. based on the orientation of the action bedded in the stock and fired from our shoulder.

 

[Molon Labe]

That’s not exactly right.

Many mount a red dot or second optic on 45 or 90 offset from gun being up right. Doesn’t matter at all.

If you laid your gun on its side, and mounted th me scope at 90 degrees, then the bullet would still behave with regards to gravity, not the orientation of the gun to the ground. Think of a gangster turning pistol to the side as he shoots.

I’m not saying it’s the best way to do it. But as long as the reticle is plumb with regards to up and down then the bullet will behave the same when it leaves the barrel.

If you were shooting at a target that was the same range as your zero that is correct.

I should have included “assuming a 100yd zero” my bad.

If you vice that barreled action and rotate rifle your point of aim will be different if you are shooting at any distance other than your zero. The bullet will have the same point of impact but it will not be at your point of aim.

 

[Formidilosus]

A lot of yall are either conflating multiple things, or confused about what is being discussed.

Wind would affect the bullet the same regardless of the roll of the rifle. And your windage changes on scope would do the exact same thing as long as your scope is level to the ground.

See this picture. Special forces offset optics all the time. The bullet is still shooting straight and dropping towards the earth curve.

View attachment 782554

Offset dots are rotated so that the bore is directly under the dot.

That is not what is happening when you have a reticle level to the earth, but canted to the rifle.


In any case, unless extremely canted to the rifle, the effect on windage and elevation is minimal and hard to detect. However, it still is a sub par method for the reasons that I outlined.

 

[PredatorSlayer]

Wind would affect the bullet the same regardless of the roll of the rifle. And your windage changes on scope would do the exact same thing as long as your scope is level to the ground.

See this picture. Special forces offset optics all the time. The bullet is still shooting straight and dropping towards the earth curve.

View attachment 782554

I am talking about windage adjustments for long range to compensate for the cant of the reticle. Short range the difference is immaterial which is why it doesnt matter for combat. Most of the time the offset optic is a red dot with a short range zero. I even have an offset red dot on my bolt coyote gun for close shots.