Rifle Scopes Help me validate my perception of gravitational physics

[EchoDeltaSierra]

OK... this is kinda nerdy, but I wanted to bounce my perception of how scope leveling applies. Let me try to explain this.

1. I have a .308 rifle, with a one piece mount, optic, and scope level mounted on the scope.
2. I have run the tall target test on this setup, 5 shot groups at zero, 5 mils, 10 mils, 15 mils and, when my scope is level and reticle are level, to a leveled target, everything tracks precisely.

Say I want to move this scope mount between guns and, obviously, re-zero the scope. If the one pice optic, mount and scope level is all setup and validated, it's irrelevant if the gun it's mounted on is a bit off-level because gravity will always pull in a level direction consistent with the optic, and the optic being 'level' is what is more important than the bore being level?

I hope this make sense and thank for your feedback.

 

[Changed]

If you shoot a gun upside down, sideways, or straight up the bullet path will remain the same. It is the optic itself that ties you to a particular orientation.

 

[Papa Zero Three]

Believe it or not, gravity isn't constant but thats a different discussion and somewhat of a pedantic comment. However, in this instance the thing you need realize is if you put that mount and scope combo that you know is level on gun A on gun B and if gun B's base holes are off, the reticle in the scope may or may not be plumb to the fall of gravity any longer. Only way to check it is to drop a plumb line once it is mounted on gun B and see if everything jives. Gravity does not conform to the optic, the optic needs to conform to the fall of gravity when mounted on the gun.

 

[Dogtown]

Believe it or not, gravity isn't constant but thats a different discussion and somewhat of a pedantic comment.

Indeed, which is why using Newtonian Physics for slingshots to naval artillery is just fine, but launching a probe to Mars requires General Relativity. To the OP, gravity is a vector in world space (0,-9.8/ms[SUP]-1[/SUP],0), always pulling downward towards the center of gravity of the Earth (roughly the center of the core). To us air fish (ie humans) living on the surface, this basically means the force applied to the bullet is always downward in that direction, regardless of how level or uneven the terrain. Technically other large masses like the moon or say Mt.Everest, if it's nearby, are also tugging on the bullet, but the relative amount is so minuscule that it's irrelevant to calculating an accurate trajectory.

 

[Sako man]

Interesting post.

There are many shooters who tilt their rifle so the vertical axis of the rifle is not consistent with gravity. The rifle is tilted for ergonomic reasons. I do this. However and as stated the bullet will drop consistent with the gravitational forces. The small offsets between the optics vertical stadia and the bores vertical axis is almost non relevant.

The major rule to follow is have the optic reticle consistent with an attached bubble level, as you have done.

Now this brings up the debate of having the level on the rifle vs. on the optic.

 

[The King]

So - it's also a little odd in that it has to do with bore offset vs level bullet motion.

The bullet always drops in the exact direction of down - the scope needs to exactly correct for bullet drop through the center of the drop arcs downward vector component.

An example:

A scope mounted 2" to the side of the rifle instead of over the bore will always correct properly provided the bullet impact was zero'd to be 2" to the side at all ranges in 0 wind. This only holds true when the rifle is perfectly level and the axis of motion of the scope turret pushes the scope tube through a perfect 90degree cross.

Where this gets triple-tap stupid is when the reticle isn't exactly in line with erector tube motion - then you can get unpredictable behavior when you shoot holdovers versus dialing. It's best to check this by firmly affixing the leveled optic to a fixture and dialing the knobs while looking through the scope versus a plumb line.

 

[Shoottothrill]

Papa three Zero nailed it.

 

[Ring]

 

[EchoDeltaSierra]

I find myself more informed and no less confused.

Say I have two rifles with rails and one optic in a one piece scope mount. The optic has a level and the reticle, turrets and level have been validated shooting groups on a tall target test. Can the scope be moved between the two guns without needing to validate its level (for the sake of 600-800+ meter distances)?

I assume the answer is yes, but wanted to validate my perception.

 

[Lowlight]

If the scope is level to the bubble level on the tube you have no issues.

You can swap it all day long with no issue.

Odds are you can shoot accurately enough to see any potential issue so it's not worth thinking about. There are so many other variables even if Rifle B was off, it'd just get lost in the noise like most things people obsess over.

 

[Griffino]

Cool topic

Funny thing happened one day in a more scientific forum...a "smart guy" once laughed at me and corrected me when I called gravity a "weak force".

Sent from my LG-E980 using Tapatalk

 

[Sako man]

Cool topic

Funny thing happened one day in a more scientific forum...a "smart guy" once laughed at me and corrected me when I called gravity a "weak force".

Sent from my LG-E980 using Tapatalk

As you know, you were correct in describing gravity as a weak force. Relatively speaking it’s weaker than most of the other forces. One exception being probably around a black hole where gravity sucks in light and shreds all matter and releases all it's energy. But looking at the forces that bond molecules together and electromagnetism, which is inverse square then yes it’s weak. The forces that hold molecules together are so strong that if ripped apart you have tremendous amounts of energy released.

 

[woostri]

Wow what a topic. Scope mounting and relativistic physics all in one. Good stuff. On the scope leveling, agree with lowlight. If the scopes bubble level is trued to its crosshairs then it should be swappable to other guns. The angle that matters between the barrel and scope is kind of set by the manufacture (ie the mounting holes). If there's error there its not something releveling would fix.

--- aim small miss small ---

 

[EchoDeltaSierra]

... One exception being probably around a black hole where gravity sucks in light and shreds all matter and releases all it's energy. But looking at the forces that bond molecules together and electromagnetism, which is inverse square then yes it’s weak. The forces that hold molecules together are so strong that if ripped apart you have tremendous amounts of energy released.

I'm really glad to see I'm in the company of other über-nerds who appreciate ballistics. I was describing to a non-shooting friend all of the math, physics, chemistry, mechanics and meteorology that (can) go into long range shooting. He looked at my somewhat stunned, and then asked if I could help him build a precision rifle.

 

[Dogtown]

It's all about having an application to apply that knowledge. For example, I didn't have a whole lot of interest in math and physics when I was in school, probably because I had nothing to apply it to, so it seemed kind of interesting but not particularly useful to me. Even as a precision shooter in the Army, going through some of the most advanced training available, I only had a cursory interest, learning only what I needed to know. Granted, back then we weren't accurately shooting anywhere close to where we are today. It wasn't until I ETSd the first time into civilian life and started working in computer graphics and animation, that it all started to click for me. Sako man can attest to this, but working in the CG side of movie visual effects, particularly as an effects animator, you become intimately familiar with math and physics. So much so that after five years of being deep in that environment, I went back into the Army in 2000 and suddenly found myself far more familiar and more importantly, interested, in the nitty gritty of the math and physics of long range precision shooting.

 

[Sako man]

Haha - all true Dogtown, all true.

The universe is a strange place but our little corner of it becomes slightly more familiar once you have a rudimentary understanding of math and physics. The problem with academia is that many teachers/professors do not tell you how math will help you down the road or even bother to show students how formulas impact us on a daily basis. It's just that -academic. We need to make it more interesting.